Oberon and Oreo get a few bites of many of our foods -- when I cut up veggies for dinner I have one on either side of me and give them odds and ends (think bell pepper tops, carrot ends, etc.) They love tomatoes -- I have one every day for lunch and they always get a slice. And whatever fruit we have they get a few bites, unless it's something like cherries with seeds and obviously no grapes. Oberon absolutely adores blackberries and Oreo will eat just about anything (including our kitchen mat but I don't think there's much nutrition in that). As far as the simple carbs they sometimes get a few bites of mashed potatoes or spaghetti if we have leftovers. During Passover they get odds and ends of matzah -- which Oberon loves (and that shows that Shelties really have no taste). Before giving them anything new I just Google is _food_ okay for dogs and follow the advice -- so no onions, garlic, etc.
My feeling, not backed up by anything, is that an occasional bite it's not a big deal but I would never expect that to be their only food.
Oh, yeah. And on their birthdays (at least Oberon so far, Oreo's only 11 months) we make a special plate of people food for them - usually a broiled or grilled chicken breast, some rice (or whatever starch we're having), fruit, vegetables; basically whatever we have handy.