People without signatures are posting because they want to. People with signatures are sometimes (but not always of course) posting purely to drop their advert again.
As fisicx pointed out, you can report it.
I think its hard to make an argument against the opinion that the quality of the posts would increase if signatures were limited to paying members
I can think of a very easy argument to make: by giving less back to valuable contributors to the forum, we may lose some good members.
That would make the quality of the posts go down.
Frankly, I think UKBF shows far too little appreciation to the members who create the best content.
Yes, all threads/posts can bring in traffic via the search engines, but the thing that keeps people coming back is the high quality advice they receive. And it's those repeat visitors that really get the forum's page impressions up.
IMO, there are about 50 key members on UKBF, without whom, this forum would be an utter joke.
By treating these people no better than self-promoters, gossips and newbies, the forum risks losing them.
I've noticed a number of them have already ceased being paid members. Some hardly post at all these days.
And now a bunch of people are saying, "Hey, let's treat these people even worse!". And, let's show how little we appreciate their help by calling them "spongers" and "freeloaders".
NOT a smart move, IMO.
I'd suggest a better question would be, "How do we better reward these people for their contribution".
Just my 2p,
Steve