Basically, if "female" is used as an adjective, it's fine. If it's used as a noun, that's a red flag. A good way to check is to try putting an "s" on the end of the word and see if it makes sense. "I wish people realized that more females drone pilots isn't actually an advance for women's liberation" that doesn't make sense, it's used as an adjective, modifying the noun "pilots." Vs. "Oh hell yes, there are some females at this bar." Oh no, using the plural s makes sense in this context, you're using it as a noun and now even if nobody else can see it, I can see an invisible fedora sitting on your head. If you can pluralize it, it's a noun.