Bitter Apple

A few questions about Bitter Apple since I'm reading so much about it on this site :
#1- Just what in the heck IS this crazy stuff?

#2- What are it's uses in training my kitty?

#3- Where can it be purchased? How much does it cost?

#4- Does it smell bad to humans too?

You can find it at most feed stores. They use it with horses who curb (chew wood) and have other behavioral issues, but it works well with other animals as well. It is very bitter- I have tasted it once upon a time and it is pretty distasteful but not harmful. It is about 2.69 a bottle here and you spray it on things you do not want your animal to get into- plant leaves, etc...

I've seen it at Petsmart, labeled for dog usage.

It hardly has any smell at all. In fact, within moments after being sprayed, I don't smell anything at all. It worked wonders in keeping my cats from eating my houseplants. I used it for about two weeks -- three years later, they still haven't taken another bite!