I had one yesterday from IRS debt relief. I waste their time since they waste mine...string them along thinking they've hooked one and then when they start asking for any personal information, I give them bogus stuff until they figure it out or I get tired of it.
I can't tell you how many of these places might have Richard Head with a zip code of 90210 and a phone number of 202 456-1414 in their database. What usually tips them off is when they ask for an email and I give them
I_hate_scammers@nowhere.com
(I spell it out [capital I, underscore, h a t e, underscore...] and most times don't get to finish before the line goes dead)