Is it bad to have spiders in the house?

Bad? No.

Dangerous? Some are.

Spiders are not as harmful to humans as many insects. They tend not to land on, or spoil, food. They don't spread the diseases that many insects and other animals carry.

In fact, most spiders are beneficial to us - because they eat insects which are harmful to us.

As to "bad" - no, it is people who are "bad".