Something else you might point out is the strategic point hoarding can have.

I've noticed someone hoarding a specific type of pet, and I've always wondered at it. I got to thinking about what advantage it -could- have for them.
If you're a hardcore trader, you -could- hoard the uncommon outcome, or a series of pets you think will be sought after in the long term, thinking it could go up in rating in the future.
Meaning: I'm going to hoard the (example, nonexitstant) Sparkleberry Swirl dog. It's the uncommon outcome. In 2 months, possibly more, that uncommon could turn to rare. Now I'll have 20-50-More rare pets to trade.
Now, not every uncommon would turn into rares. Or, even rares that someone would want all the time. But...if you plan well, I can see how finding a pet, or series of pets, that people are raving about, that's aesthetically pleasing and well liked, could very well be sought after in the future by people who are newer to CS. Even newbies can get rare outcomes you know, so they might just be willing to trade them.

((Meaning, never discount the newbies!))
Just my two cents. I'd, personally, never hoard. I don't see the point in it, besides strategic value, but I personally prefer to have only 1 pet, and maybe some in trades. But I wouldn't go crazy for it, nor drive my brain crazy trying to figure out which is tomorrow's winner.
