Not sure how trendy these are.
1. I have seen some really well done fan art. What I don't like is that many people don't realize that fanart can (and in my opinion should) be in the artists own style. If you carry the major features and characteristics that make that character what he/she/it is, people will know who it is. Hell, I'd be more impressed that I know who it is and your style is nothing like the original artist's own.
2. I don't like that people piss on cartooning because they are tired of seeing anime. (In many many cases, the artists' style isn't what is defined as anime anyway.) Many of these people will also assume that because an artist chooses to work in a highly stylized fashion, that he or she can't do anything else. Good cartooning comes from a knowledge of real life and simplifying it to get the message out clearly in a more iconic fashion. Some people can do get the same [removed](and make it quite interesting) with a couple of lines as someone who can paint a photoreal painting. Cartooning still takes skill, design knowhow, creativity, and planning.
3. This really irks me.
Assuming that digitally coloring your art will make it any better and/or thinking that it covers up the weak areas of the image. We can still see all the problems. In technicolor.
4. Futa. I find transexuals to be a beautiful illustration of mankind's ability to shape his/her own fate, regardless of the circumstances. I also have a lot of pictures of transexal women who have kept their penises. So, it's not that I have any issues with gender bending, but there's this trend in certain communities I'm a part of where every chic must have a p***s. And I'm not talking about a women who was born biologically male. I'm talking about biological women with vaginas that magically sprout penises at will. And use them to rape other chics. (I have yet to see a dude sprout a v****a, though, I have noticed that a lot of the yaoi artists like to make the poor guys with self lubricating asses, which can't be comfortable). Tt just rubs me the wrong way.
5. Rape porn in general. This just makes me sad because it's often made sparkly and romantic, with postures that indicate intimacy and not what it really is. Abuse. The 'vicitm' never fights and she's usually a chic with huge saucer eyes pooling with light and a single tear running down her cheek. Petals flowing in the background. And underaged looking. Sometimes, I see them and silently hope the artist is gang raped and THEN beaten beyond recognition. They can draw another picture and we'll see just how sparkly it is then.