Personal Experience with peppers
My mother had real problems with deer a few years ago. They've gotten really bad around here and subsequently she's been buying flower types that the deer don't like to eat. Well, she was given some rose bushes. After only a few days, the bushes were nearly gone. She sprinkled a bit of powdered cayenne pepper directly on the flowers and the deer didn't eat it.
I decided to see if I couldn't find out a better method. The deer probably don't like the smell or taste of spice and subsequently don't eat it. Well, I looked up how to extract capsaicin (the active ingredient in chili peppers that gives it the spice). The best way to extract it is 200 proof ethanol, AKA normal drinking alcohol. I didn't have any 200 proof alcohol, but I had some Everclear (95% alcohol, 190 proof).
We sliced up peppers, the hottest we could find, stems, seeds, and all, and put it in a pot. We filled the pot until the top of the pepper pieces were soaking in the alcohol. We let it soak for an entire week. After a week, we strained out the pieces, poured the liquid into a bottle and sprayed it on the flowers.
The smell of peppers is very powerful and the spice is pretty potent. It's like making pepper spray at home. I would highly recommend this as it's easy to do. 151 would work well too, probably.
A word of warning: be upwind when you spray this. It doesn't hurt, but your lungs will tingle for a few minutes if you breathe it in. But it's VERY effective. She was like the only person with flowers that deer liked to eat (like roses) in the entire neighborhood.