> That being said, I always try to be respectful when I get one and politely reply. Always remember there's a person on the other end trying to provide for his/hers family.

Eichmann was also trying to provide for his family. Respect is something you earn for not being mediocre.

I personally think that it's not a good idea to reply to anything unless you are actually interested in it and wish to do business. You are wasting your own time, you have to provide for your family, and theirs that could be better spent actually making money and doing deals.

Normally I'd agree. But some email you regularly (eg every few weeks) until you respectfully decline. Granted that's infrequently enough where I could just ignore it. But the disruption to my workflow getting these emails is enough to warrant registering my disinterest (I prefer not to mark the messages as spam on services I'm not interested in but may come to need at some point in the future).