I work for a company that makes nutritional supplements including weight loss supplements (not one of the companies mentioned and board rules say I can't tell you who I do work for).
The FDA is slow to take action against any company but a lot of the more visible supplements out there are sold by small companies that aren't big enough for the FDA or FTC to care about. They go after big money. That's also why a company can produce a bad product for years before any action is taken. The government takes action after they are making enough money to be worth their effort.
For the consumer this sucks because there is no protection where you need it most. To help protect yourself I recommend you:
- Avoid sites that are single product sites
- Never do business with a company that doesn't publish their address and phone
- Read the fine print on the return labels, and
- Look for reviews of the company or product that are not on their site
That won't rule out all bad product, but will certainly improve the odds you get what you want.