Spencer,

I have noticed several people talking about cleaning spray zones with ammonia based cleaners to confuse it with a "marking".

This confuses me.

Ammonia and cat spray have similar smells to a cat - because of this I have always used an ammonia free cleaner. This stops the cat from spraying over freshly cleaned areas.

...am I thinking correctly about this?

Annibale16, the length of a cats coat is also an important factor of allergic reactions. Remember that allergies are for the most part a black art and it is very difficult to identify exact causes in many cases. Some peoples allergic reactions to cats will dissapate within days of permanent exposure to the culprit, others will never get used to them. The typical allergic reaction to pets has the symptons of puffy eyes and itchy nose, the reaction will also be very soon after exposure. Many people have mild reactions to animals and don't even make the connection. I have a mild allergy to cats but have decided it is worth the discomfort