Sometimes raw pork and chicken don't give off an odor or change colors to let you know it's gone bad. Yet, it's been in the refrigerator a few days and it's past the "use by" date. How do you know whether to use it or lose it?
Mom taught me to touch it. If it's sticky - it will have a definite "tacky" feel to it - toss it out. If not, it's still edible. By all means however, if you can't get beyond that "I don't know" feeling, toss it out anyway. Better to be safe than sorry.
I use the government's "sell by date" as a gauge not as a definite indicator of spoilage. Meat and dairy products don't spoil the minute it passes the sell by date. Meat and dairy (except eggs) can be frozen until you're ready to thaw and cook it.