I don't know, I've had tons and tons of clients over the 20 years I have consulted. Off the top of my head, 80% have been fine, 10% run in to issues now and then, but there's a hardcore 10% that will stretch you and stretch you because they can (I'm talking about paying NET 60/90 when the contractual agreement is NET 30).
If you withhold services, you usually lose that client. To be honest, that's not always a bad outcome, because a bad or slow paying client is usually the noisiest, most demanding and most unreasonable one as well.