Costco (COST 1.68%) offers low prices for its members throughout the year. During the holiday season, though, the warehouse club really steps things up with some deals starting in mid-November, additional sales that kicks in digitally on Thanksgiving, followed by more discounts on Black Friday.

Prices will be good on many items, but you still need to be careful when shopping at the membership-required warehouse club. Not every deal is as good as it seems, and there are a few items that you should shop for elsewhere.

These may not be the only Costco shopping traps that pop up this holiday season, but they are likely the biggest. Heed the warnings, and you'll have a better chance at keeping everyone on your shopping list happy.

A person shops in a warehouse.

Costco offers lots of great deals but there are a few you should be wary of. Image source: Getty Images.

1. Avoid clothes

The merchandise selection changes regularly at Costco. That means the shirt or pair of pants you buy as a gift may not be in stock for someone to exchange if the person you purchased it for doesn't like it or needs a different size. Clothes could still be returned, but do you really want to buy someone a sweater and have them exchange it for bulk-sized cereal or something else that's not really in the spirit of your gift?

2. Be very wary with televisions

Costco generally has good prices, but it's usually not the cheapest when it comes to picking up a deal on a TV. There are exceptions, but be sure to do your homework to determine the features you want and ensure you're familiar with the price range of TVs that come with those options. When you go to buy, make sure that the model you're considering isn't a slightly different model number with missing features.

3. Pass on that mattress

While the warehouse club sells mattresses, it generally stacks them vertically rather than setting them up for testing. It's not a great idea to buy a mattress that you haven't tried. Even if it's for a guest room, you're better off buying a bed from a traditional mattress store, where you can lie down on several before making a choice (and prices are aggressively low at some of those mattress chains right now).

4. Be careful buying jewelry

Costco has a limited selection of jewelry, which means you should buy it as a gift only if the recipient has signed off on the purchase. That may take away the element of surprise, but it prevents you from buying gifts only to have the people you give them to not like them, and then have trouble finding something they want to exchange it for.

5. The giant teddy bear (and other novelties)

During the holiday season, Costco often has some truly silly items, like giant teddy bears. It might seem like a great gift for a child, but honestly: Who has room for a five-foot stuffed animal (and who really wants one)?

In general, think twice before buying anything out of the ordinary. Consider whether the gift will be valued or whether it will just be a good story after it has been opened.

Use common sense

Warehouse clubs can cause people to make stupid purchases because the prices are low at any time of the year. Buying a cheap kayak is a great idea if you live near water and will actually go kayaking. It's a bad idea if it becomes something that sits in your garage.

Don't make purchases just because there's a great deal -- make sure they're things you or someone on your gift list actually needs.