I have not only had many a springer spaniel (DH was avid bird hunter)with floppy ears (dogs, not DH) but was a swimming parent for eight years. I don't know if they suffered from the same infection but swimmers suffer from what is called "swimmers ear" and team parents all swore by the alcohol/vinegar as a preventive. Primarily it just dries the ear out. So what if your kid sells like salad dressing. I've used the same preventive on the spaniels. The reason the Monostat works is that the dog is suffering from the same fungus we ladies get. Vet pointed that out to me. For a while there I was medicating one of the springer's ears and vagina at the same time. That was tricky as vet recommended we do that while dinner was ready so she wouldn't lick away the latter.
My vet always sniffs at the dogs' ears when they come in for annual check up or any ear complaint.