EndreWhiteMane: Disclaimer: I love dogs too, have had one or more for the last 55 years of my life.
Now, not sure where the whole sugar thing came from. Dogs use sugar, whether simple or derived from the digestion of carbohydrates, the same as we do.
Too much leads to obesity, dental decay, etc. How much they can have depends on their activity level, just like us.
There are many foods that are truly BAD for dogs, onions can't be digested, chocolate is toxic, and there are 10-15 others on the no-no list.
Sugar however is not any better or worse for dogs than it is for us, which is bad in excess.
Carbohydrates in food, can be readily digested with no problems. rice, wheat, cereals in general, dogs can and enjoy eating them.
It's processed table sugar that can cause problems, their digestive system deals worse with high concentrations of fructose than ours. Basically it's relatively easy to cause diabetes in a dog by giving him sugary treats regularly.
But yes, it's not toxic or anything. And not necessarily bad in small adequate doses. I admit, it's somewhat overblown.
I've been looking up stuff. Part of the whole, "candy is bad for dogs hmmkay?" argument is due to xylitol, which is an artificial sweeteners, which again is not precisely healthy for them.