If the author had succesfully registered Sherlock Holmes as a trademark back in 1875, and kept efforts at protecting and re-reggistering that trademark continuously, then yes it should be a trademark, just like Bass is. A trademark isn't just the name "Bass" though, but clearly if someone else created a beer called Bass they'd have a job on to explain how it's not the same Bass that Bass trademarked.

Trademarks protect the consumer as much as the buyer. The only reason someone would want to put two "golden arches" on their burger joint is to make people think it's mcdonalds. That's bad for mcdonalds the company sure, but it's also bad for the customer who thinks they're getting a certain "standard", and do not deserve a counterfeit good.