I'm pretty good at avoiding spoilers. Partly because I tend to know what to avoid, and partly because I have a terrible memory. Often if I do hear a spoiler I just forget about it.
The only thing I can remember being spoiled for me was Death Note, but it wasn't really a huge deal. I kind of expected the spoiler, and the show is more about how they get to that point instead of what actually happens. The person who spoiled it for me actually forget they had and decided to spoil it a second time too. That's probably why I remember.