Can I block someone who gives me useless answers?

Click on their profile, and there is a block option there

Yes you can Block someone who gives you a useless answer. They won't be able to answer your questions again when you do.

Another thing to do is if the useless answer does not answer or even try to answer your question then you can report that answer.

You can block them or just report them.

Yes you can, but why bother? Just ignore them.

if they're not posting anon you can