Dirty bottles CANNOT be sanitized. So, when someone gives me beer bottles, I most definitely remove the labels and SCRUB THEM OUT THOROUGHLY with a bottle brush. Even heard of someone who puts the bottle brush into an electric drill and then uses that to scrub out the inside of the bottle.
Once the bottles have been cleaned to my satisfaction, I use them to hold beer. If I can't get all the "gunk" off the bottom of the bottle, it gets thrown away. When one is emptied, it is THOROUGHLY rinsed with hot water. Since they were clean in the first place, a thorough rinse is all that is needed at this time.
When I bottle, I run 54 bottles through my dishwasher WITHOUT SOAP on the "high temp wash" and "heated dry" cycles. When the washer is done, I let the bottles sit for a bit to dry/cool off. Then, I put my bottling bucket on the counter above the washer, and using the open washer door as a low "shelf," I proceed to bottle my beer. Cleanup is a snap: close the washer door! And no bottle infections yet!
glenn514