Now, certainly some offers that you receive are truly worthy of consideration. And I certainly have some respect (and perhaps pity) for the underpaid minions hired to make the inconvenient marketing calls. (I can't say so much positive for the scamming spammers, however.)
The telemarketers, canvassers and spammers market with the numbers game. They figure that if they make enough calls or send enough emails, someone will bite. The cost per lead influences the strategy, as does sales training for the telemarketers and copy writing skills (and coding abilities) for the spammers -- especially successful ones that are able to evade your spam blocks.
I have a simple solution for these operations and virtually all inbound solicitations. Ignore them UNLESS they can in their first sentence identify a credible person who you respect as a referring source, and provide a real reason for doing business with them.
Heck, that is a blunt rule, but it has a corollary. In your marketing, unless you can achieve the same relationship focus with your outbound direct sales calls and messages, you should stop, take a cold, hard look at your priorities, and reset your strategies. (Unless they are currently working, in which case, well, I suppose you are succeeding at the numbers-game approach to marketing.)
If you rethink the process then you will see how a much more effective direct sales marketing campaign can start -- with your existing, truly satisfied clients.
Ask them for their help in spreading the word. Obtain referrals, references, and reputation back-up. Then you can call -- and drop the names which matter the most to your potential clients (outside their own names, of course.)
Does this approach work? Well, most of our own sales result from phone calls, faxes and emails. Many are to people with whom we have done business in the past, but at least 25 to 30 per cent a month are brand new potential clients. However, we always call on reference from someone they know and respect. You can do the same thing, yourself -- and ignore the others.