Are you talking about casual sex only or do you do this for relationships and people who you date too?
You're just picky and we all have our type/types of person/people who we are attracted to and the ones who we are not attracted to at all. I don't see you being shallow for just having a preference or if you state who you are not into, or who you are into.
Everyday I see personal ads online where people write things like:
"No fats or femmes", "Sorry I'm not into people 10 years older than me", "I'm into white men only", "Latin a ++++", "love uncut cock!", "I only like thin men", "be muscular", "No thin men", "No fat/BBW", "be female, fit, and physically active", "Sorry I'm only into people who are my age", "into black men only", "Sorry I'm not into twinks", "I am attracted to white VGL men my age, that's my sexuality", "I'm not into butch women", "I'm not attracted to women at all, just men", "No Transmen", "I'm not into women with exessive tattoos/piercings", "I like men who completely shave their body or are smooth", "Facial hair is necessary", "Looking for 8+ inches", and there are other examples that I'm sure you can think of.