I quite often use the reverse bookings to pad out a long distance booking if I know I'm going to have some free time before or after. From what I have been told, the clients do look out for an interesting pitch, so do write something flirty/friendly in the box (more than just directing them to your profile, at least), but that might just be my clients! It will almost certainly mean compromising on your rates a bit, but I have got two local regulars out of it (who pay my full rates now!) as well as trips away and three regular London clients who would almost certainly not have seen my profile otherwise.
If you scout them fairly regularly you will begin to recognise the ones not even worth looking at, (barebackers, general oddballs, complete cheapskates) - look out for feedbacks just as you normally would. I can recommend them for making up the numbers if you have a trip planned, a quiet spell or fancy travelling about a bit.