Now a days, I get persuade by others opinions to watch certain shows but that has no influence on my expectations of the show(s).  I usually just tell myself that it's above mediocre and I don't give it an exact scoring until the end.  And like Slushba132 said, "If it sucked it sucked.
If it didn't then is was probably awesome." and I totally agree.
Before, I use to get pictures of random animes and if it look cool or interesting, then I would watch it and see how it was (that's how I found out about gurren laggan, code geass, haruhi, rozen maiden, and clannad).  It's a strange way of doing it but it worked for me.