Technically, my complaint would go to any book that has an interaction with people. Since it mostly happens in romance books, that's why I'm titling my article thus.
A couple are being all passionate, and he sweeps her against his broad chest, and kisses her fiercely. Problem; he's six foot two, she's five foot four.
I just don't understand how a tiny little thing could be pressed tight against her lover and have her mouth devoured. Granted, I haven't been five for four since about the sixth grade, and don't remember it very much. He'd have to pick her up, wouldn't he? I stand next to people eight inches taller than me, and I can't envision it.
Nor can I envision him tucking her under his chin without having to really crick his neck. She just wouldn't be that tall compared to him. She'd come mid chest, if that.
Which means it sometimes throws me out of the story when these events happen. I am suddenly asking myself how it's possible, instead of joying the passionate moment. I stop, and mentally reconstruct the scene, trying to piece the couple together.
Because it bothers me, I'm now putting extra effort into making sure how my characters are aligned. Not that I have a lot of couples that aren't close to the same height. But it's something to keep in mind.
What are other little things that bother you that you now look for?