They are more likely reflected people not desperate just to make a few quick bucks. If you attract these kinds of subscribers and treat them well mailing list you will develop a great friendship and loyal customer-base for years to come. I am on a number of e-mail lists (35-50 haven't the exact number) because I can always learn new things from them.
But I can tell you that about 75-80% of the e-mail lists I am on NEVER provide anything of value, they just try to sell me stuff and some of them mailing list with no ethical standard's at all. Some of them send out several e-mails every day and NEVER give out anything of value. I don't know about you, but I would never consider to bye anything fro them.
After 5-10 e-mails I hardly ever read any of them any more. But a handful of the e-mail list's I'm on I read EVERY time because they bring help and value to me in my work. I even bye from them occasionally because they have something I mailing list would like to learn and it can bring my business to the next level. That's value. To illustrate it I can use Frank Kern as a brilliant example.