Mise le meas and all that. You could try spotting the duds at the very start and thereby avoiding all this trouble. A wedding ring may indicate that he is married. Also a white line across his finger where he was wearing his wedding ring before he started chatting you up. If the answer is yes, run for your life girl.
Bastards are the hardest to spot because they can be very charming.
The person who invents a bastard-detector will make a million. But I don't seem to be able to keep anything in my memory. It's a long time since I did any exams, I'm afraid. But I think you could try reading a section of stuff you need to know or going through a problem or whatever. You will be able to remember things.