I'm thinking about going tubeless using Stan's sealant or equivalent. I'm aware that sealant should be added time to time and am wondering what happens to the innards of the tire over time? Wouldn't the dried sealant accumlate in the tire or does it all evaporate away? If it does accumulate, how often must it be cleaned (removed)? How messy is this cleaning process? I'd appreciate comments from real world users very much before I decide to go tubeless.