we buy a lot of these as promo/schwag materials for our business (ridewithgps.com, a bike software website/apps) and they certainly do wear out. I end up rotating mine our after 6 months, and i do not wash them with anything but the soap + water + shake method. the lining wears off and you are left with a plasticky tasting bottle. even new, if you let them sit with water in them for a couple days they'll taste slightly of plastic, so it's not perfect.

much better than any others we have tried though, so worth it.