To answer the original question, no I haven't ever been on one of those vacations, but yes, they do sure look tempting.
I would think that they would be quite pushy. It's not actually a "vacation" but a sales pitch. Most of them say you will only have to endure a 90 minute presentation, but being they are paying for you to be there, it would only make sense that they would be pressuring for sales.
Now that I think about it, I remember a friend who did one of those many years ago. I recall there being a "processing fee" for the so-called free vacation.
I think it might be ok if you are very much able to resist salespeople. If you are the type who can't give a firm NO, or walk away, then it might not be worth it.
For me, I cannot put "vacation" and "sales" in the same sentence. The word "sales" just doesn't equate with a good time.