Drugs of any kind that make you not think straight have absolutely nothing to do with having sex with animals. It is dangerous for the animal since you are quite likely to make a mistake in such state.
Other than that I believe that if you regularly need to rely on any kind of mind altering substance to live your life, it is a sign of mental weakness and often plain stupidity.
Cannabis has legitimate medical use if used responsibly though, so I do not hate it.