I've owned both types. I don't know if being perfectly horizontal has anything to do with it, but I've noticed with that type, after final spin when the tub rotates slowly to loosen the clothes from the sides, it's an exercise in futility. The machine in question is a Frigidaire Affinity. When we had a Whirlpool Duet, that one had the tilted tub and the clothes always loosened up nicely after final spin. I'm not 100% sure, but the Affinity may have a spin speed of 50 rpm faster than the Duet. Whether the speed or the tilt have anything to do with the clothes sticking to the sides, I don't know, but that's my $.02 observation on tilted vs. non.