After 30 years in the business I have had a fair share of these types.
Early on I fell for one and parted with 50 quid, only to find the ads chucked out the back of the shopping centre. I risked a court case not paying any more but called their bluff with a photo.
Basically only pay for advertising that YOU have enquired about. Stay with the recognised media, always look in customers homes to see which directory, if any, that they have. Some areas are good for Yellow Pages, some for Thompsons. Round here Thompsons is US. Estate agents etc. calendars are a nono.
ALWAYS ask the customer where they found you. Keep a note on your enquiry form and look at this monthly to see whats working and dump that which aint.
Trevor