There are no terrible cards, only terrible duelist. If you are calling cards terrible you should really rethink your duelist career cause it means you sucks. At least, you aren't as good as any protagonists. But the truth is, all cards can be good or terrible. Depends on who uses it. My chemistry teacher got to KOG last season with a deck focused on summoning Slifer the sky dragon and that really
Not always. I like the optimism, but this is not an anime. Real life has metagame, and not all cards will be good in the current metagame.
For example, a duelist who cannot use B.E.S. cards in OCG/TCG meta does not mean the duelist is terrible. It's B.E.S. that are too weak for current OCG/TCG meta, having been powercreeped to hell ages ago.