You can add a TM to your string or add verbiage in the footer of your site indicating that RobMonster.com is trademarked, for example.
As to whether a regulator such as USPTO will issue TM on a .COM, the fact is that they have. Amazon.com is a registered trademark. Which means RobMonster.com can be a TM as long as it is not confusing similar to some other registered mark.
In other words, someone with a generic name like John Smith might have a hard time getting a trademark for John Smith because many exist already:
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However someone could still get a TM JohnSmith.com.
Epik is planning to make more progress in providing registrants with more comprehensive brand protection solutions. Some people know that I am Chairman of Patents.com. The key will be to make something that makes it is easier to buy, sell and lease these trademarks. That is really the missing breakthrough. We do it with domains but for TMs this is relatively novel. More to come there.
Rob