I chose a dentist from the Yellow Pages because their advert said they were a good helpful practice for nervous patients. This was 'The Tooth Place', Ipswich UK. I stayed with them for a few years, thinking they were presumably pretty normal. I never felt comfortable having anything done by them. Their idea of a good chair-side manner was pretty-much 'Relax. RELAX DAMMIT. Be sensible..." (accusingly) "I'm not doing anything to hurt you'. I'm slightly spastic. Relaxing on command is so not going to happen. If I needed anything tricky done they sent me to Colchester (20 miles away) because the dentist in Colchester could do sedation. They didn't do anything to encourage me to be calm or relaxed apart from telling me to relax, and that it wasn't hurting and was nothing to make a fuss about. (I knew it wasn't hurting: it was the fact that I was getting more and more tense that was the issue). When I had a root canal there I felt nervous: I hate having things far back in my mouth in case I'm going to gag, and I felt I had no control over the situation as dental tools and suction devices were stuck into my mouth with no attempt at warning me (I felt like an awkward bystander as the dentist talked to the assistant over me).
I stayed with them until they dropped me for forgetting one too many appointments (I tend to find it difficult to remember things six months apart). I didn't like going to the dentist but I thought it was always going to be like that.
At this point, I went to the practice my boyfriend uses, and my dentist is now Miss James. She is very kind and reassuring, she lets me stick my hand up if I feel nervous so that she can back off for a moment, she's never hurt me (even in longish filling procedures -- I haven't got a root-canal incident to compare), and I've never felt guilty because I'm a bad patient--which I felt all the time at the other place. She's wonderful. She seems to think of details the other dentist never did: giving me a moment's rest in case of nerves, putting dark glasses on me so I don't get the sense of FREAKOUT INTIMIDATION DENTIST LIGHT :-), letting me know what's going on and what's going to be going on.
I have my checkup appointment in September on the kitchen calendar, iCal and my Blackberry so as not to miss it, on the principle that dentists who make me feel less-worse about going to the dentist are worth their weight in whatever.
It's not necessarily bad service, but it's useful information: if you're a nervous patient it's worth finding a practice that you feel comfortable with, even if the one you try first advertises that it's good at putting patients at ease.