I'm not sure on the deterrent effects of cigar nubs, but nicotine is a very powerful poison. Works great as an insecticide (I make it into a spray described above though probably use it a little more concentrated) and in large enough doses can take out other small creatures. I have unfortunately seen a few dogs and a cat die because they were given either cigarettes or chewing tobacco to deworm them. In all of these cases they were given quite a lot. I doubt sprinkling crumpled up cigar left overs is going to pose a danger to any dogs or other wildlife and if it keeps them away from your plants :thumbsup:.
Dan