Get it wrong, not compatible

When a man approaches you, you're in a position to find out if he's worth the time of day or not: you can interrogate him about what he does and what he likes and see how comptabile you are. However, if you make the first move on a gorgeous specimen who turns out to be a loser with a capital L, by the time you realise he's an idiot it's too late to avoid an embarrassing situation.