A cautionary tale
This is the story of one application, but it's like many we've seen.
A business owner wanted to register his trademark. A search of the Trademark Office database showed there was already a registration of pretty much the same word for the same services, but the guy went ahead and filed an application anyway.
He paid the Trademark Office $975 in filing fees.
A few months later, he heard from the Trademark Office: They wouldn't register his trademark because it was confusingly similar to a trademark that was already registered. The Trademark Office also said if he didn't respond by the deadline providing "arguments and/or evidence as to why the refusal should be withdrawn" his "trademark would fail to register, and the application fee will not be refunded."
End result: After several months and a pretty chunk of change, his trademark was still not protected.