How to tell if chicken has gone bad?

I bought some chicken wings today, and today was their sell-by date, so they were a manager's special. I was cooking them today, so wasn't too worried. When I opened the package, the smell of "chicken" was really strong. They didn't smell BAD, but I noticed a very strong smell of chicken. I'm probably being extra wary because of the manager's special sticker, but is this chicken safe to eat?