Also here's a pet peeve of mine. When a person, gm or not, doesn't read your character all the way through and then proclaims them to be a mary or gary stu. For example if a character is really well liked and has some very much weaker versions of a move that is higher class. Perhaps they get a really huge reputation for something they have or have done. Then forget to mention that the guy or girl in question hates tactics, is biased against certain groups, fights almost exclusively in one area, can be easily overwhelmed if his weakness is pushed against, and or is simply not book smart. Other weaknesses that could be attributed to characters with other strong traits could be stuff like a prodigal level soldier with a genetically weak body. lack of charisma, any sort of hampering disease, drug or alcohol problems, and otherwise really severe problems.

When I personally come by and look at a character I look at what they are capable of doing currently and in the future and if I see something I don't know how would work I either ask about it or say that I don't feel comfortable with that sort of ability in the roleplay.