There’re so many examples of bad logos below. But I want to try to make it something bigger than just a “don’t make a logo looking like a backside or a porn picture” kind of tip. So, here’s my list of the worst logo designs.

Plagiarism. Look what they’ve done to the adidas logo! It’s a shame, breaking the law and just stupid.

Too plain. It’s not always a bad thing. But in the case of the example, it really says nothing and it’s hard to read.

Abstract. People can’t understand what it means and how it is connected to the brand.

Just ugly. Sometimes ugly means outdated, that’s right.

Too many details. Just imagine how it will look on your business card. Not a good idea at all.

Unfortunately, even “experts” sometimes create horrible logos. In case you want to save money and time and create a logo yourself, that’s a good idea. I’ve collected the best logo makers and the rules on how to create a good logo yourself. Following the tips, you won’t come up with any of the logos I’ve mentioned in the answer. Good luck!