Renting out timeshares for a profit is MUCH harder than it looks. I am a timeshare addict (there, I've confessed it) and own way more than I can use. So, I rent some out. But it is tough, tough, tough, in this economy.
There are a ton of factors working against timeshare owners who want to rent. A lot of renters want just a weekend, not a whole week. Even if you could find another renter for the weeknights (which you probably can't), many resorts are just not set up for having two different parties in one unit in one week--they may not have a way to clean the unit, may have no way to charge phone calls and incidentals to two different parties, may not even be able to handle two reservations for the same week.
If the resort will handle rentals for you, then you may be able to rent to several parties per week. But more likely, you will end up with just a few nights renting, and it may not be enough to cover your MFs.
Most of the public don't understand timeshares. You will get a ton of people who ask you to change your fixed Saturday-Saturday week to Sunday-Sunday. You will get people who think you are a hotel and won't give you a definitive answer until 8 pm on the day of check-in -- by which time the front desk may be closed.
The big problem, though, is marketing. Probably 90% of the public doesn't even realize they can rent a timeshare. Of the 10% who do, many of them are afraid you will rip them off or that the place will be a dump, and will not rent from a private owner.
I think most Tuggers who make money renting timeshares use points systems, not fixed weeks. But most of the timeshare systems that are in points (Wyndham, say), may never be worth much on the resale market. So, buying now for cheap, renting out for a while, and then selling, probably won't bring in much profit in these points systems.
There are some fixed weeks that rent for way more than the MFs, but these are hotel-brand timeshares in highly desirable locations and times-- a Hawaii Marriott at Christmas, say. No one is giving those timeshares away.
Also, don't forget you have to pay your MFs at the beginning of the year, then wait until maybe July or Christmas before you receive your rent. That ties up money that could have been used elsewhere.
I know why you find this tempting. I keep getting tempted to buy more timeshares. (Like I said, I'm a timeshare addict.) The deals are SO hard to pass up. But anyone thinking of this, be warned -- you may end up doing a ton of work just to break even. That is what has happened so far to me. I hope that when the economy recovers, I will be able to sell the units for more than what I paid for them. But, even if that happens within a few years, the return I'll get per hour of my time may be pretty low.
... If you want to make money renting with no contingencies, then find someone who wants to rent their week; get their set asking price, and find a renter at a higher price and keep the difference.

Then you are not held to MFs / usage if you cannot find a renter at more than the MFs/asking price.
Kaio, if you accept money from your renter BEFORE you pay the owner for the week, you will be acting as a real estate broker without a license, which is illegal in most states. It is legal to pay for the unit and then try to rent it out for more than what you spent, but there's a big risk the unit will sit empty and you will be out what you paid in rent.