I can't say I have come across a bad host in a while myself however back when I first started out I used GoDaddy which I at first thought was a great host but then the problems started, bad customer support and really poor uptime. I am not too sure if this is still the case now but from that poor experience I wouldn't go back to them and use them as a host.
For awhile I had a personal grudge against my current host provider cause of their slow reaction to billing dispute that nearly shut down my forum. But it's been awhile so I'm all good now. I can't think of any specific company I'd say to avoid. Probably one that offers too limited of bandwidth for traffic or has lots of down time.