Why have a rant about it? Just don't answer. That's what everyone else does.
Some guys need to get a feel for the person they are going to book first and ask a few questions. All your rant does is make those people think that their pm's won't be welcome and put them off all together.
If someone sends me a pm with 'Hi' and nothing else then I'll just ignore it, the same as I would if it was a text, but you can't lump all clients as either time waster or client. Some do have other things to consider as well and need to ask a few questions and feel that you'll get along.
So sure, I agree guys that are just after a 'chat' are wasting their time, but not mine, as I'm not going to respond.
It always makes me laugh when people talk for the masses, like their opinion is the same as everyone else. You can only talk for yourself in this life.
Oh and if a guy offers to take you out for a drink, why not suggest them to book you for a dinner date and give them your rate. That might work out well for both of you.