Let me tell you a little story. When I first started working in the field of real estate, I had a great idea for generating business. I decided to respond to all those spam emails I received with the following information: I was a homeowner, my home was worth $1,000,000.00, I had a current loan balance of $200,000.00, and I needed cash fast, so I wanted to get a loan for $800,000.00. If requested, I'd tell them that my credit score was in the 700's. I represented the perfect consumer.
Needless to say, I'd get a phone call immediately from a lender. When they called, I'd break the bad news to them. I'd tell them that I wasn't even a homeowner, but was instead a title attorney trying to get their business. Some were understanding, but others were furious. You see, they didn't actually send me the email. Some spamming service sent it and received my response, which the spamming service then sold to the lender. So, not only did I get to make a sales pitch, but they had to pay to hear it.
I realized very quickly that this probably wasn't the way to do business. If I angered all the lenders, I'd never get any referrals from them.
You, on the other hand (and me with respect to other spammers), are in a very different position.
If we all respond to the spammers, running up their advertising bills, it becomes financially impractical for them to use spamming services to advertise. The spamming services then lose their business and go broke. The result: no more spam.
There are two potential drawbacks.
#1: Most of the spam requires you to enter a phone number. If that's the case, either you're going to have to put up with a single call from them (at the end of which you tell them never to call you again), or you have to give them a fake number. If that number is unlisted, okay. If that number is the local pizza parlor or FCC hotline, see #2 below.
#2: I haven't researched the legality of this practice. My gut has me concerned that it could be some sort of misuse of telecommunications technology -- especially if you're giving another's phone number to the spammer -- which could result in civil or criminal penalties. On the other hand, I'm responding to their request addressed specifically to me. I wouldn't be a bit surprised if there were a way to do it that's 100% legal, or if illegal, never enforced or impossible to prove.
One of these days, I'll probably get around to researching the legality of this practice. In the mean time, I have work to do, and you shouldn't practice it unless you've gotten an attorney's advice on its legality.
Sooner or later, we'll get the bastards.