I always tell my female friends that if a guy tries to get you on the back of his bike and doesn't give you a helmet, jacket and gloves, makes you wear pants and boots (at least tied shoes) and/or doesn't go over ground rules while on the back of the bike, tell him to fuck off, he doesn't give a shit about what happens to you. If he is not wearing gear himself, that is an automatic no.
Can't really do anything about someone lying and saying they are a safe rider. But those simple things to think about should weed out a lot of dbags.