Paul.. this is an area I have experience with. I've been with this forum a long time.. Please heed this advice..
To answer your question, yes, of course there are people with fake FB profiles pretending to be females who are males. The same is true on this site, and all over the internet. I'm a male, by the way, and people who have talked to me from this site, and met me, can confirm that. I never claim to be something I'm not. 43 year old straight white male, that is me. .
My advice, just talk to people, and don't worry about it. If you DO encounter someone you like.. the following needs to happen.
As quickly as possible, within... a week.. or two.. you need to make confirmation of that person;s identity, via phone, and webcam, and set up a meeting as soon as possible. If they refuse.. move on.
Those who know me know the situation I'm referring to. I didn't heed this advice, and allowed myself to get dragged along, by someone who claimed they were female.. and who I now have every reason to believe was a male, and who proceeded to drop out on me, at a very difficult time in my life.
Just talk to people, and have fun. If you do find someone who you want to take things further with, follow the advice I gave you, and which I didn't follow, to my own detriment. I've heard of people who do actually meet partners on sites like Facebook or this one, but caution and good judgement, which I didn't do, need to be exercised.
Good Luck