If someone asked you to write all the brands of X that you've ever used, can you remember all of them, especially if they were nearly equivalent in quality and use case?
I might forget about Aquafresh or Close-up or something, but I'm pretty sure that I would remember Crest and Colgate- especially if I was a dentist. It's like leaving Honda off a list of reliable cars. Hard to believe it's an accident for any reasonable sample size.
