Here are a few items that irk me slightly in the wonderful world of comics. Don't take this too seriously - this isn't a major rant, and these things only usually nibble at me due to over-use. Coming next will be Things I Do Like in Comics.
Gun poses (usually "pin-ups") - women with guns, men with guns. Guns in general irk me with their proliferation, especially when used as a solution to all plot problems (in films too)
Gritted teeth, or always-shouting-characters - especially when also holding a gun
Female characters that are always dressed like, well, prostitutes, when they're not prostitutes. You know, like pop stars. What happened to a bit of dignity and class?
Artists who computer-draw over photographs, and claim they don't. Particularly the use of 'adult photographs' as 'reference'
The words 'arc' as in 'story arc', and 'season' to refer to a run of comics - I know this is completely irrational
'Cool ingredients' just for coolness - these include monkeys, dinosaurs, zombies, robots, nazis, kung fu, girls, ninjas etc... They are usually combined, eg. 'kung-fu zombies', or 'nazi monkey robots', and the word 'giant' may also be inserted. Comics with these often don't include a storyline, thinking the concept is strong enough on its own
Word balloon tails that cross over because the characters are on the wrong side of the panel for correct order of speech. Bad storytelling and it jars