I find QL a very interactive site.....if u stop PM or even restrict them you would be losing the whole concept(like qatai rightly pointed out)

In some societies/cultures people take liberal(free spirits)women as objects of sex. So mostly PM them looking for the same. Some take their chance on every female like you pointed out.So an appropriate way of dealing with them would be to invite them over to our QL gaterings and politely explaining to them that this is not the way it usually works.....just an idea (invite at your own risk;)

Life is too short and if u r not living on the edge then u r taking up too much space.