How to Prevent Quacks

There are many products on sales these days and sometimes we cannot judge which one can help us. Sometimes we care so much about our health that we suddenly agree to buy those quackery unintentionally. And here are some useful ways to prevent them.
1. They treat illnesses that generally have no cure.
2. They offer money-back guarantee.
3. Their products are for many illnesses.
4. They invite you to read testmonials.
5. They promise quickly exciting cure.
6. The product/treatment is in a secret way and is only available from them.
7. They say doctors/the rest of the medical community are against them.

However, we buyers must be careful before buying any products. Some points are also used in advertising by real products.