When we engage in sexual relations with a partner, we want to know that the person we're with is healthy and clean. It certainly gives us peace of mind to be reassured by our partner that as far as STD's go, we have nothing to be worried about.

But what if you can't trust the word of your partner? What if they aren't telling the truth about their sexual health? Or worse still, what if you don't bother to ask at all?