I think that kinda of defeats the purpose of you working for them. In a sense I guess you could call the company a "pimp" and the workers for the company that pay them the "hoes". I only use this as a reference because its the only "job" that i know of where the employees have to pay their boss to work.
I think my friend that is a tattoo artist would be troubled to hear you say that.... He has to pay a small fee in order to work at the tattoo parlor. But after paying that monthly fee, anything he makes from his clients is his alone. I think some carnies work under the same principle; you may have to pay a small fee to the fair / carnival but afterward anything they make is their own money. Also many
strippers dancers work under the same model, but that may be getting closer to your original analogy...
Similarly, some on-line businesses (Avon has been mentioned a few times) require a small fee but then anything you earn is your own money. However you have to determine what the fee is going towards before declaring it a scam. For my friend the skin artist, he pays the tattoo shop a fee that goes towards building rent, utilities, advertisement, etc. There are also other shops where there are no fees for this stuff, but then the shop gets a cut on all sales that the artist makes. Similarly, I could see an on-line business charging a small maintainence fee for their software, space on their servers, etc. but any sale you generate from the web-site that they give you is your own earnings. A different business may handle those maintainence costs differently by not charging you any fess, but then taking a cut off of your sales.
I've also heard some people mention that selling educational / informational material is just a scam, esp. if that information can be found for free... But this too may have an underlying reason behind the fee. Even though the information may be found for free, time is money, and if it would take you several days doing the research for yourself, it may actually be more worthwhile to pay a fee for that information rather than spend so much time finding this "free" information yourself.
Thus I'd never say that all of these businesses are scams; although this does tend to be the case more often than not. So I'd say to be cautious about these sites. Check the BBB, Google them to read up on any complaints, and determine the reason why the fees are necessary. In the end, no one is forcing you to accept any of these jobs, so even if after doing your research and the company seems legit, if you still don't feel comfortable with it, then just skip it and move onto something more suitable to you.