No, Redweek is definitely not a scam. It is still one of the best websites out there and one of the most cost effective ways for Owners and Renters and Buyers and Sellers to connect.
Yes, some owners / brokers may leave ads up to gauge interest or an attempt to turn into sales leads.
But at least a part of the issue is that Timeshare rentals and sales aren't usually completed in a day, or sometimes not even a week or longer. From the time an owner is contacted by somebody looking to purchase, it could take a few days to a couple of weeks to get a sales agreement signed and escrow funded. Same is true to a lesser degree or get a rental contract signed and payment submitted. And many owners have experienced people who say they want to rent their unit, only to send that person a rental agreement and then either not hear anything back for a few days, or sometimes not ever. This delays the process for everybody and isn't the case of an Owner trying to mislead anybody. Or owners run into Buyers that take longer than expected to fund escrow, because most of them have 7-10 days to back out of an agreement.
Basically it takes some time to complete some of these transactions. Yes, the Owner can (and should) make notations to the ad, but the Owner can't really take the ad down until they reach the point in the process where they are sure it's Rented or Sold, and they have some assurance of payment in the form of funded escrow or receive payment personally. Nothing is final on a Rental or Sale until payment is actually made.
Some people who are new to Redweek, or only recently joined, don't understand that timing dynamic. They think just because they respond to an ad, that they are somehow automatically entitled to that specific rental or sale they responded to. But they are may have just been a little too late to get it. Good deals on rentals, or sales of good units at fair asking prices sometimes go very quickly. This has happened to me as well. I have responded to ads I was interested in and responded just a little too late to get the rental or purchase.
The same dynamic is true with literal real estate. Anyone that has ever went house hunting has probably experienced responding to a listing they were interested in only to find it recently went under contract, or the Seller's decided to pull the listing, or they raised the price, or whatever. But enough time had not passed for the listing to be updated yet to reflect that.
Sometimes it's nobody's fault. It's just a function of timing.