How do you rate your customers.

Do you rate your customer by the amount of work they give you ... size of the projects or monthly turnover?

Do you rate them on how fast or slow they pay the bill?

Do you offer a better service to the ones who pay quicker?

DO you move a customer up the waiting list if they pay in advance and do they get better attention?

What do you do with the slow payers ... increase their hourly rate to compensate for the losses due to interest and bank account fees ... or do you just dump them and focus on the good paying customers?