you gotta be smart about your rotating meat. there's a lot of places to choose from, so choose wisely.
1. if it looks like dog food, it's probably dog food. or dog.
look for discernable layers. the pate-ish ones are mostly filler, maybe cardboard. if you can see texture and pattern, you can rest assured the dog meat is mixed with other kinds of dog meat. or vegetables? even better.
2. the bigger the better
notice the width of the meat tube. if it's like a small hippo, or young american, it's fresh and good. if it looks like a skinny mangled sausage just clinging to the spit, it's been there for a while. go somewhere else, come back in a few days to see the fresh plump version.
3. it's apparently ok if the guy uses his hands
don't cringe when the dude picks up a stray potato or slice of meat with his fingers and puts it in your sandwich, or cuts open your bread with his fingernails. only us foreign americans are all creeped out by bad hygeine. keep your cool, blend in with the locals.
4. make sure it's sliced fresh.
don't get the pieces lying in the pan, sliced during the dude's last cigarette break. point to the meat tube, make slicing gesture. a good place will give you the pieces about 105 degrees clockwise from heat coil.
5. no electric knife slicer things!
that screams "shortcut" to me
6. say no to any tea from behind the counter
if you can water it down yourself (there's a little hot water spout under the tea ball thing) then you're ok. but if you're served it with no option to alter the potency, it's probably the battery acid variety, beware of immediate stomach cramps.
7. try, try again
for statistical significance, your sample size must be twice the standard deviation. you can't pick the best doner after only trying a few of the bigger places. you need to hit every single one, at various stages of progression (see #2). even the one in the u bahn station, even the one that no one else goes to. you never know where the best secret meat tube is hiding.