I did well with CL my first season. All of my clients were great and had minimal tire kickers.
As mentioned, giving them something to look at other than a classified ad helps weed out the cheap bastages.
I use an actual ad in the form of a hosted image. This also helps to avoid the spambots from picking up my email address and phone numbers since they can't "see" them. (but a human reading them can, so getting spammed is still possible)
I ran an ad early last season and again early this season, but got less desirable inquiries than I did initially. I find that by using keywords at the bottom of the ad I get calls for weeks and months after having run the ad because people do a search and my ad will come up - even if it hasn't been renewed for a while.
All that said, I'm liking the inquiries I'm getting from Angie's List a lot better.
I've had a few that said "Oh, whatever it costs is fine, I just need someone reliable - the guy I found on Craigslist never showed up."
I can't say that I've ever heard a CL caller say anything like that. LOL