Mary-Sues and Gary-Stus. Sometimes it’s really obvious when you read it in people’s drafts. The hansom mis-understood something (werewolf or vampire 90% of the time), encounters completely “speshul” snowflake woman/girl.
Vampires. Supernatural anything as well. It has been done and it was done well (as far as vampires go I stopped and Bram Stoker’s Dracula), however I am yet to read any new stories in these genres that are good.
David Eddings does the plucky hero, chosen one very well. Raymond E Fiest does high fantasy very well. Peter F Hamilton and Ian M Banks have sci fi (among others) tied up. So to write those two pure genres well you really have to work hard to create something different.
Try-to-hard strong female characters. Polgara from The Belgariad etc was fantastic… too often I see the strong female character go so far away from actually being a woman that you end up stuck reading a character that doesn’t do anything but try too hard at being a man. And then when the author wants to put in some female traits it then can come full circle as a Mary Sue.
Also if I go into a Sci-Fi or Fantasy section of a book store I want to see Sci-Fi and Fantasy. If there isn’t a space colony, future tech, knights in armour, barbarians and wizards then get out. Supernatural romance is a genre of its own at this stage and I think the sci-fi and fantasy section does need to be filtered a bit more.
Yeah, and you can get off my lawn too…