I suppose there could be some variables at play as well. If you received a very clean [used] keg and your cleaning practices were good and you also happened to have soft water, your keg may stay in very good shape. Some of my kegs were purchased years ago when AIH was selling used ball-lock Cornelius kegs for $15. Some looked like they had been stored at the bottom of a lake. Yes, I cleaned them well but I also have high bicarbonate in my water and shower doors, faucets and the coffee maker all show signs of it. I am now 50% of the way through my kegs... filled one last night with boiling water and EasyClean and left it until this morning. A very light scrub with a green pad and it looks brand new now... sparkling clean and no buildup at all.