Writing question

So I was brainstorming a couple of writing ideas, and an interesting question occurred to me:
If you've got an idea that sounds superficially similar a TV show/movie you've heard a lot about but haven't seen, is it better to watch said show/movie to help make sure you're not ripping it off or if you should avoid it altogether so you can at least be confident that you're not knowingly doing so?

My tweets

• Sat, 17:07: RT @DalekThay: CYBERMAN, CYBERMAN. WEIGHS the SAME as a MINIVAN. METAL SUIT with a BRAIN. About as SUBTLE as a TRAIN. LOOK OUT! Here COM ...
• Sat, 19:52: I hate when I miss a spot shaving. Even if it's not visible to the naked eye I still know it's there.
• Sun, 01:22: RT @adembskibowden: In Alterac Valley chat: [Fearboner] has joined the battle. Good name, guy. Really... uh.... really good name.
• Sun, 05:29: Writing question http://t.co/nRY0ERis
• Sun, 05:45: RT @wonderella: I guess the world ended again today, but we didn't collect enough emeralds to get the good ending.