> Best not to get them expressed by a person at this stage, unless the dog is very uncomfortable, as the more often you get them expressed the more they will need expressing.
I tend to disagree - IF these glands are the problem, and if they are clogged/infected, if left they could rupture. I do agree to routinely manually drain these glands unless needed (they will refill in any case) can encourage a greater need for this to be done. Working as they should these scent glands shouldn't need touching. BUT if the dog is scooting, it suggests clogging and in that case, a vet (not a groomer) should drain them and check what's going on - and treat if needed (may just be one side that's a problem).
The fishy smell comes from the glands, and if it's on the breath, would only be because the dog has managed to get to the area to lick!!