What is the worst scam you've ever fallen victim to (or come close)?

A couple of years ago I badly needed to see a dentist, but I didn’t have insurance. Aspen Dental advertised payment plans and competitive pricing, along with a free first visit. It was irresistible to someone without dental coverage.
Well, my “free” visit consisted of probably 50 x-rays (which badly cut up my mouth, and I was blown off about my concern about it being too many x-rays), a hygienist violently stabbing me in the gums, and then a dentist tearing out my one and only filling. Then they proceeded to tell me that I had severe periodontal disease that would cost me in excess of $4000 out of pocket to treat. They insisted that they could not fill my tooth (you know, the filling that they had torn out) until it was treated. Then they told me that all of my teeth were going to fall out in a couple of years.

I would have probably believed it, except that they told my husband (and the other two people getting check-ups that day) the exact same thing. Ultimately, two other dentists confirmed that I don’t have a hint of periodontal or gum disease, and that a filling could have been done even if I did.

Needless to say, I’m left to this day wondering how the place stays in business with such sleazy practices.

What is the worst you have ever been scammed? Even if you didn’t fall for it, what is the worst that you’ve encountered personally?