I love my Better-Bottles. They are a cinch to clean and sanitize. NEVER attempt to clean the inside with any kind of brush! You will scratch and ruin them! To clean, I rinse out whatever gunk I can with water. Then I add enough PBW for about 5 gallons and add about 2 gallons of hot water. If there is any stuck on krausen and junk I insert a wash cloth. Then I shake the crap out of it until all the stuck on stuff is removed. The action of the rubbing of the cloth, hot water and PBW have never failed to get off even the most stuck on crud! Then I fill it up to the top with hot water and let it sit overnight. Dump it out, a thorough rinse and it's done.
To sanitize, I pour in about a gallon of Star-San solution and roll it around for a couple of minutes to coat the entire interior surface. And that's it.
John