The pay for something is usually related to the demand for the job, as well as any danger or unpleasantness one must undertake in order to do the job.
Demand: Work-at-home jobs are desirable for many reasons, because everyone from stay-home moms to laid-off workers wants an “extra source of income.” The supply of workers is high, so the pay will be low or nonexistent.
Danger: Work-at-home is usually pretty easy, with incredibly minimal demand placed on the worker. You don’t even need to get dressed, and you don’t have to pay for gas to get there, so the pay will be very low or nonexistent.
However, because of the high number of people looking for this sort of situation, the hopeful workers themselves become a resource just waiting to be milked. That is why so many of these things are scams. People will fall all over themselves to get work-at-home, and are easy marks for people who want credit card numbers. And all an unscrupulous person would have to do is offer a fake “work at home” opportunity and rake in all the suckers.
There are real sites, but the “pay” is low and incremental. You can do surveys for points, say, that you redeem for prizes (like DVDs) or for low cash (like $5 every few months, which my husband was all excited about when he did surveys every day). There is Mechanical Turk from Amazon, for example, which is reputable, but is it worth your time? Only you can be the judge.
And whatever you do, “stuffing envelopes at home” is a scam. :) You read the ad, see that you can send a few bucks for info, do so, and wait. What you get back is permission to put the same ad in a paper, charging a few bucks from people hopeful for an envelope stuffing job. The “stuffing envelopes” part comes in when you reply to the people with permission to place the same ad…
Good luck. It’s a scammy scammy world out there. And if it looks too good to be true, it most likely is.