I have a 100oz. MSR dromedary bag that I have had for years, and I actually used it for quite some time as a bladder for my hydro-pack since my old one busted. (which, by the way, I do not recommend the MSR drinking tube and adapter for the MSR bags - the two that I tried both leaked and I had to use a hose clamp with them). Anyway, I always experienced a bit of plastic/rubber taste with that bag, esp. when in hot summer temps. Not overly offensive, subtle, but there nonetheless. Very well built bags though, and I will continue to use it for back-up water. I have abused mine on lot of backpacking and paddling trips. Scott, did you notice some taste to the water on the Prescott Overland trip? My memory fails me at the moment, but I thought I had gotten some of that taste from the MSR bag you had in your truck too.