Bears have a much keener sense of smell than sight, and although I read something anecdotal about such a study, I'm not sure the conclusion was exactly as you stated. Do you have a cite for the article?

Anyway, camouflage tents do exist. For example, I have an ECWS tent that was made for the Marines by The North Face. The main body of the tent is woodland pattern, and it has two flies: one woodland pattern, and the other all white. You can also find them with desert pattern flies.

Bibler and Integral Designs both make single-walled WP/B tents for special operations forces, and I have seen them on eBay in woodland pattern camo. You may be able to find on the Integral Designs web site a mention of their camo tents.

Also, eBay often has military surplus tents from Europe in camo patterns.

The reasons why I'm not much of a fan of camo tents for non-military operations are twofold: I want a brightly colored tent so I can find it easily and have a "cheery" interior ambience; and secondly, I don't want to be mistaken for a paramilitary nut case. BTW, the EWCS tents have a blackout coating on the inner side of the fly that makes the interior absolutely pitch black--even during the day. Useful for operations, but pretty gloomy unless you have a lantern.