There is a difference when treating well-known trademarks (say Coca-Cola, Sony, Google), however I doubt Waffle House gets over the threshold set for that for being too local (I counted at least 20 states that do not have one) and not sufficiently known by all demographics (if you want to know more read up on the Lanham Act).
Full disclosure: I am a TM lawyer, but not in the US. YMMV and what I write here is no legal advice ;-) since only gathered from US colleagues' explanations regarding cases clients had in the US.
The notorious/well-know concept is part of an international treaty (Art. 6bis of the Paris Convention) and its interpretation is similar in most western countries, so I'd expect the US interpretation to not be that far off.