Each shard has a different level of saturation in the various pet markets.
In stark contrast to Atlantic, Europa tends towards giving cu sidhes away (yes, whites/blacks/ice blues/rose pinks, etc) unless perhaps on the slim chance they also happen to be uber in stats and/or resists.
Since I am usually unable to find homes (even free of charge) for average stat/resist "rare" colour pups, I tend to cull them off, too, unless someone speaks up or, of course, if I am aware someone is specifically looking for something in particular.
Note:- This is neither right or wrong, better nor worse, nor even good nor bad - it's just the way of it.
Learn your market. Ask around, speak to your fellow tamers you encounter whilst taming and see what (if any) is the right critter for you to be taming with a view towards profitable pet sales.
Don't be shy about asking advice, or discussing best sellers and even prices amongst your peers. Chances are you may just snag something he/she has a buyer for and vice versa.
Itchy backs are more easily remedied when there are more than one set of hands with which to scratch.... Know what I'm sayin'?
Good luck & good hunting, Kal-In-Ex!