Monty is also a member of the niffy ear club! Since the start of this awful wet weather he has begun to "pong" a bit!
Having checked all the obvious i.e. lip folds, inside ears etc., I found the smell was coming from the bottom section of his ears - which he constantly trails in muddy puddles!
I have started to wash his ears off after walks (I pop the bottom section into a plastic jug and give them a gentle swish around) and I add a gentle shampoo a couple of times a week. I was horrified by the colour of the water the first time I dipped them in the jug, no wonder they smell! I towel them dry as much as I can and give them a quick blast with the hair dryer set on a lowish setting. So far so good, things seem to be improving, but if I miss a day the pong is back.