Heres what i do with any Potential form of advertising directory.
Pick five numbers form the directory and ring em, people will tell you if they are crap as people love to moan, but they also like to brag about how good a business decision they made if things are working out. It takes 10-20 mins and could save you hundreds of pounds and using this method ive always had a return on my advertising that ive paid for. Another good way touched on earlier is to call 5-10 members of your family or friend and ask them where they look when they need a tradesman, ive none of them say Yellow pages then dont bother, if most of them say "your local parish mag" then go for it.
Ive avoided some bad apples using this method such as, 118 Trades & the satins own UFINDUS.
Dene