Infomercials that sell shampoos, zit creams and the latest weight loss gadgets can be hard to turn away from. But before you pick up that phone, you should know that the low, low prices and easy monthly payments advertised are not always what you’ll pay.

“There are many problems with infomercials,” says Edgar Dworsky, the editor of consumer resource guide ConsumerWorld.org. “Not all of them are misleading, but many are.”

Leaving aside whether the miracle products really work as advertised (some do, but always check out online reviews at Amazon.com or elsewhere), you have to be careful and aware that the $19.95 price touted often will wind up being a lot more.

One popular tactic: adding high processing and handling fees. The company behind the Snuggie, Perfect Bacon Bowl and other “As Seen on TV” products agreed to pay $8 million in March to settle charges that it deceived customers. The Federal Trade Commission said costumers were led to believe they would be getting two $19.95 products for less than $10 each, but actually paid $35.85 when a handling fee was added. Allstar Marketing Group said it always believed it followed the law and said that it has made changes to make costs easier to understand.

Still, bad players are out there. Here’s what to look out for:

Stealth subscriptions: Read the fine print. Some marketers will automatically put customers on a subscription plan. That means customers will be charged periodically to ship products. This is especially common from those hawking face creams, hair conditioners and other beauty products. In the infomercial, a warning is often written in tiny print under the price, says Dworsky.

Easy payments? Expensive gadgets are sometimes broken up into “easy payments” that makes the product seem cheaper. They might say, for example, you’ll pay $39.95 in four payments, adding up to $160.

Buy 1, get 1 (not): Freebies can be far from free. A “free second item” can sometimes come with high fees. Before making a purchase, customers should ask the company what the total charges will be.

Upsell! If you buy a product online or over the phone, you may be pushed to buy extra items you don’t need. If you fall for it, you’ll also likely pay extra fees.

‘Trial’ period: Be aware that free trials aren’t forever (and sometimes trials aren’t even free), and ask what the cost would be if you decide to keep the product. “The price shown is often just the price of trying the product,” says Dworsky. “If you want to keep it, a much higher price is charged.” Also, be clear on what you have to do if you return the product and ask who pays for that shipping.