1. Red Bean Paste: This is at the top of the list because I see it so much, more so in fic than in RP. I don't care what the Bleach wiki says: RED BEAN PASTE IS NOT ORIHIME'S FAVORITE FOOD. Her favorite foods are listed as 'cheese and butter'. Don't believe me? Here:
In fact, she only directly eats red bean paste once, here:
For some reason, this scan says 'bread and honey', but the Viz release says 'bread and sweet bean paste'. The scan has the right idea, though, so let's talk about it!
See, I made it blinky so everyone will notice it! Have you ever been to an Asian grocer? I have! I've been to quite a few! And in every single one, there is red bean flavored something (or somethings) for sale! There is red bean mochi, red bean paste, red bean buns, and even red bean ice cream! There's even red bean mochi ice cream! And it's all from Japan! It's a common flavor! So having Tatsuki, Rukia, Ichigo, Chad, Keigo, Don Kanonji, and his DOG turn green at the mention of eating red bean paste is kind of like having people turn green at the mention of eating... honey. Or strawberry jam. Or mayonnaise. Sure, some people don't like it and some people may be allergic, but all food is like that.
What you need to take away from this is that Orihime's taste in food isn't 'disgusting' so much as it is 'strange'. Take a good look at that profile page again - do YOU find anything particularly 'gross' about eating butter with sweet potatoes? I sure don't, because it's friggin' delicious. In fact, if you take a look at the things we know she eats, they're just combinations that are either based on puns or seem to be the result of being raised poor (which is further backed up by the fact that the only other person to enjoy her cooking is Rangiku, who was raised eating persimmons). Honey and wasabi in ramen? Sounds like that's all she had laying around the kitchen that day. Red bean paste on bread? My step-mom's family was so poor they used to eat sugar sandwiches, and I still eat mustard sandwiches. Parfait and egg over rice? It's a pun.
As a suggestion, when I'm making up stuff Orihime likes to eat, I just start with a base - say chicken - and add a fruit or vegetable - say avocados and pineapples - and maybe add a spice - say curry. So the end result is avocado pineapple chicken curry, which is weird as hell, but fun to imagine someone eating. And best of all? It's not red bean paste just like everyone else's fanfic.
2. Little Blue Men Once again, we see this in a lot of fanfic (and rarely, but it's still present in RP), but it's shorthand for a much larger problem. It's often brought up in the context of:
Orihime: *trips over her own feet*
Ichigo: Inoue, what just happened? Are you okay?
Orihime: It's alright, Kurosaki-kun! It's just those pesky little blue men being mean to me again! Did you know just yesterday they set a wire trip trap in my living room that set off spy lasers attached to sharks that have relays with the purple penguins in Chile who then pushed the shiny red button that triggered the death ray satellite and that's why Second Impact happened and Antarctica exploded off the map!"
Ichigo: *sigh, she's so cute~ ♥*
I WISH I WAS KIDDING, but what I just typed is so typical that it could easily be dropped into a whole helluva lot of IchiHime fanfic and not look out of place at all. Let's go over what's wrong with this scenario, shall we?
A. Orihime doesn't do this in the manga. Let's take a quick look at how Orihime's imagination actually works in the manga:
No penguins or little blue men or death lasers involved! In fact, all of those things are situations you could see in regular movies and tv shows, which is honestly probably where she gets her ideas. In fact, the absolute weirdest her imagination gets is right here:
And that was a dream.
The truth is that while these situations seems kind of bizarre at first blush, the first situation demonstrates pretty clearly how her imagination works. Stuff doesn't come out of thin air, the situation flows from one scenario to the next, like a word association game. It's easy to see how she went from a date in the park with Ichigo, to racing Ichigo to the see-saw, to racing Ichigo in the Olympics, to outrunning a black guy, to beating a boxer, to almost getting assassinated by a fan. Just because the other characters aren't privy to her thought process doesn't mean they don't make some kind of sense.
B. Orihime doesn't actually believe this stuff is real. She doesn't believe she's a boxing champion, she doesn't really believe there are purple penguins. And for goodness sake, she doesn't think she's really going to grow up to become a hyper-destructive robot. That was a PUN - even Michiru points out that she misunderstood the assignment (Orihime drew her 'future' self like how the Jetsons are the 'future' nuclear family). There's a huge difference between imagining crazy stuff and actually believing the crazy stuff you imagine is real.
About the craziest things I can see her actually believing (and this part is pure speculation on my part) are things that people actually believe in real life - UFOs, conspiracy theories, alien abductions, Bigfoot, all that jazz. But even that doesn't mean she's going to believe aliens are trying to trip her, which brings me to my next point...
C. Word Salad The above example is actually an example of a kind of Word Salad, or schizophasia. It's nonsensical words strung together in a way that doesn't make sense but is still grammatically correct. We all know why writers do this - they think Orihime is 'random' and just throw funny words together to simulate this effect instead of actually putting any thought into making what they're writing make sense. But the sad truth is, if someone sounded like this in real life, it'd be a very serious symptom that they were schizophrenic. So not only does it make Orihime look like she should be on medication of some sort, it also makes the other characters look very strange for thinking this behavior is 'cute' or 'charming' and normal for her. In fact, in real life, if a person talked like this, most people would be repelled from them, because it's highly unsettling, so it throws off the whole dynamic of any relationship you have her entering into.
Or worse yet, when lazy writers make her say things like this... and then use it as an excuse to have other characters annoyed by her. The less said about that the better, I think.
The best way to avoid making Orihime look completely unhinged with her fantasies is to clearly draw the line between fantasy and reality with her. Orihime knows the difference between fantasy and reality - show that she does! If you want to write her saying something crazy? Preface it with "I saw a show once..." or "I read a book once..." or even "I had a dream once where..." There are some pretty damn strange shows out there that would be right up Orihime's alley - having her explain One Piece or Adventure Time would fit her character perfectly. Everyone has crazy dreams from time to time, but she seems to have a lot of them. Have her share them!
3. Manic-depressive Orihime While I rarely see Orihime being written or played as bi-polar, I'm referring more to her being written as either manic to the exclusion of all around her or a total emo bucket.
The truth is, neither is right. Orihime's shown to have a whole range of emotions over the course of the manga, mostly being influenced by her perceived self-worth and the people around her. What she actually is, is a Stepford Smiler - someone who hides her bad feelings (in Orihime's case, her insecurities, jealousy, and loneliness) behind a perpetual happy face (in Orihime's case, so people won't worry about her). That doesn't mean she's lying when she acts happy or that she can't genuinely feel bad about things. It just means that she tries to hide those bad feelings from others so they don't worry about her.
This presents a particular problem in RP because RP is entirely made up of interacting with other characters - it's hard to show Orihime's emotional depth in this situation because she naturally hides all those bad feelings when talking to other people. So instead of seeing that she might be sad or lonely, all anyone is going to normally see is happy, smiling Orihime.
So savvy Orihime players have to make an extra effort to give her that extra emotional depth, or else she's just going to seem like any other genki girl. You can do it in bracketed comments or you can have her get close to a person and let her guard down a little. You can even have her misspeak very occasionally and show some of her worry and concern. Because she doesn't wear her heart on her sleeve, it might be a little hard to get around to it at first, but as she gets closer to other characters, she can open up.
Those are the big ones I can think of. If anyone else has anything strange they've noticed, feel free to drop it in the comments!