Depends on what you mean by "off" really.
Only because some would equate dry with off rather than properly off.
If it's really off, the fatty part might have a slight vinegary (thats how I think of it) smell to it meaning that the fat is starting to go rancid.
Old pork can also smell a little on the "gamey" side - not so much off, as that it might have a strong taste (think of the difference between pork and boar - vvv similar, but also vvv different.
I'd say that if you're at all unsure, it might be safer to bin it.
Also, theres a similar issue with pork thats been frozen too long. People think that if it's been in the freezer then it's got to be OK - erm, I'd say not.
You often find, that plassy bags containing frozen meat have been split (on the corners etc). The meat might have been frozen, but if you look at it, you will see areas that have been exposed to air (albeit frozen air) that have dehydrated (think of those prog's on discovery about "ice mummies"). The meat can still be cooked ok, but the areas subject to the dehydration will be very tough, with a disagreeable texture.
So the same would (IMO) apply. Bin it.
The above isn't AFAIK, backed up by fact, just my own experiences where I've managed to screw up with storage of meat etc.
HTH a little.