I hate car alarms. Noone pays attention to them any more because 99.9999999% of the time, they are going off for no *!@#!#% reason. Even the people whose alarms are going off don't pay attention to them. This bugs me to no end. I have actually considered throwing a brick at a car whose alarm keeps going off, just to make the alarms existence seem justified.
Here is a suggestion. If your car alarm goes off every time a mouse farts, fix the !@#$ thing! If your worried that something might get stolen out of your car, don't leave it in your car. Thieves won't break into a car without looking through the window first, and if there isn't anything in there worth stealing, they won't bother. If your worried that your car will get stolen, get Lowjack.