Garlic, herbs and spice/chilli certainly wont do any dog any harm in moderation, may give them the shits a bit but it certainly helps towards keeping them worm free imho....I have now got the worming periods extended and they never have worms (I think one instance in I dont know how long)
I would rather keep giving them spices of various kinds than worming drugs.....as has been said, I suppose kebab meat fed exclusively possibly may not be ideal, but as part of a good mixture of everything I think it would be fine.
In the winter, I will melt down a block of lard to pour over the dogs dinner.