There are two types of clients. The "warm fuzzies (wf)" and the "cold
(cp)".
The wfs like everything. They ooh and ahh and can't praise your work enough. They buy all your special offers. The cps, on the other hand, hate everything, are always trying to get you to drop your price, add more work, and so forth, and then they don't like the finished product when it is delivered. The trick to being a success in business is to be able to tell up front who is a cp and who is a wf. Then you pass the cps on to your competitor while you relax and enjoy life doing business with the wfs.
If you ever read Robert Ringer's books on sales, you'll also be able to identify with the above. He divides potential customers into three groups, but essentially the first and 3rd group corresponds to the wf and cp. In his methodology you still deal with all three types but you deal with each differently.
As far as trust, the wf is always trusting (sometimes to a fault), so you must be gentle with them and never take advantage. The cp wouldn't trust his own mother, so you must be sure never to trust them either.
cheers,
rfs