1. You are not financially stable. Pets are expensive. Food, care, etc all add up. Please don't let taking care of your animal infringe on taking care of your real family (spouse and kids).

2. You do not own your house. If you are renting, you should NEVER EVER own a pet. In this housing market you are severely reducing your chances of getting a place. Your family needs to come first. I have an in-law who had to live on the wrong side of the tracks because that is the only place that took pets. They had small kids at the time and had to choose a dumpy trailer. This all happened before the housing crisis. Stupid, stupid and more stupid.

3. You don't teach the animal discipline (especially dogs). I can tolerate your dog if it's well disciplined. I hate your dog if it jumps up on me, sniffs my crotch, or barks at me. Plus, the animal is probably destroying your home. Carpet, couches etc are being destroyed by your animal if there is no discipline.

*EDIT* 4. Leave your pets at home. The people you visit say it's ok to bring it, but don't believe them. Pay to board it. Also, animals do not belong on any sort of transportation vehicles.

The conclusion: there are way to many people who own pets that have no business having them. Many are doing it to the detriment of their families and their own well-being.