99% of dogs never have an issue and honestly none of my dogs ever have had an issue. Just know that once anal glands have been expressed manually by you, the vet or the groomer, they usually will always have to be. The key is finding a food that will not give them the runs, and feeding them fiber. We feed Orijen Dog Food, and previously have fed California Natural, Solid Gold Barking at the Moon, Nature's Variety, and Raw and have never had an issue. Yes, some will expel them when they are scared (that is a good thing - you want the anal glands to express themselves by themselves). The key is feeding a good food, keeping a dog at a good weight and them getting plenty of exercise. My Boston Terrier and Mutt have never gotten their expressed by the vet or groomers. If we smell the fishy smell, they get some fiber rich foods or the tablets and within a day, their glands are expressed. The only people I have ever known that had to get them removed or had issues were those that allowed others to express the glands. So, rule #1, don't let anyone do that!!
For that matter, I have never had my cats have issues either so I don't know why so many feel that they manually need to be expressed so much.
I agree that it is a gross topic! Good Luck!