We fill all Bell's growlers and blank growlers, as long as they are clean.
Please note that we do not have an in-house "growler cleaning" station and we have the right to refuse any dirty growler.
What's the best way to clean your growler? Upon finishing the beer, give your growler a rinse with hot water. If there are any lingering odors, give it another rinse. Then let your growler air dry unsealed. Popping the lid back on right away will trap moisture and could potentially lead to mold growth.
Most dishwasher and dish detergents will leave a film inside your growler, which could impact the flavor of the beer and make it difficult to fill (foam....foam everywhere!), which is why this is generally not recommended for the best cleaning practices. For the truly funky growler, white vinegar is a good alternative to soap, as well as Starsan cleaner from a homebrew supplier.