You can tell by it has a wet tail if you never wet her tail and its wet all the time then you will know they got a cold once you notice that take it to the vet
I don't have much experience, but I THINK that my hamster has a cold. I THINK that because it sounds like it's sneezing. If your hamster is sneezing, go to a vet.
You can tell if your hamster has a cold because it may be shivering and very scinny.