How many cats is too many?

[Measure Zero]

I've had to ask myself this question recently: how many cats is too many?  I know that someone with one or two is probably not exhibiting a problem, but I also know that someone with 20 cats probably has some issues.  Hence, this poll.  When I hear that someone has X cats and that person does not own a farm or a pet shop, for what values of X should I be worried?

[Thomas Kerwin]

It depends how large your property is.  Plus, if you live in the country, even if you don't have a farm, you can support more pets of any kind. 

(Maybe not jaguars.)

[Measure Zero]

By farm I actually meant any kind of multi-acre property.

[BobChuck]

gah. There's a perfect Harvey Birdman quote here, but I cannot find a clip of it.