OK, I have one hive w/ 2 deep supers and a shallow super sandwiched between them (started this past spring w/ 2, but ended up combining them). The hive is wrapped in tar paper. Going into fall, we fed fumagil medicated syrup, but the bees were disinterested in it and took very little.
We've had unusually cold temps this winter. It's been well below freezing for the last 3 weeks or so. Noticed that the outside of the hive is getting pretty spotted w/ bee droppings. There are only a few dozen bees dead outside.
The upper entrance is really stained.
One source that I read said that if the hive was lightly discolored (and what the heck is lightly discolored anyway? mine looks pretty spotted up to me), not to worry. Another indicated that seeing this in January meant the hive was doomed.
So, which is it? I have not looked inside...temps are supposed to moderate by the end of the weekend/early next week...
Most of these things are not black and white. If it's been really cold for some time and the bees have been holding it, it's not unusual for them to let it go on the way out. If you see those kinds of stains when it's nice out, then you have problems. If you have enough of them, you might get worried, but how much is too much? Depends on how many bees you have, how long they were forced to hold their feces because of the cold etc. If you don't see a lot of dead bees I wouldn't worry too much.
A lot of you seem to spend a lot of time worrying about whether or not it will get warm so the bees can void. Whether or not they are doing ok.
I do check when it's snowed to clear the botom entrance, and I check on warm days to see if they are flying, because on a warm day, if I see something wrong, I can do something. On a warm day when they are flying, I can feed them or put in some Apistan strips etc. But if the bees aren't flying, there's nothing you can really do anyway, so just relax and see what you have on the next warm day.
Don't sweat the stuff you can't control.