I'd like to think I couldn't be, but I think there are some very sophisticated chancers out there.
I do remember 4 years ago, I was contacted through a networking organisation I belong to by a man who seemed charming. I answered him once, but knew he was dodgy. An older friend, who was also a member of the organisation mentioned chatting online to a man and described the bloke who had contacted me. I didn't have the heart to tell her he was a fake. Fortunately, she told her son about him and he put her right.
I think once we get past a certain age, any online 'romantic' contact is liable to be a catfish. There are so many older women and far less older men. The catfish see us as easy game.