I've seen this claim in other places on the www.

A search at the US Patent and Trademark Office for Trainwreck and Train Wreck showed -- BBK Tobacco & Foods of AZ has a trademark on trainwreck for "Cigarette paper; Cigarette papers; Cigarette rolling papers; Cigars". Otherwise, there's a long list of TM for jeans, bracelets, restaurant services, dominos (the game,) etc. under the name using both spellings.

For Purple Kush there is a line of clothing and Akrum Alrahib of Az has a mark for FLAVORED TOBACCO, CIGARS, CIGAR WRAPS AND CIGARETTES

For LA Confidential there's a make-up case, bathrobe, electronic publishing services, t-shirt, comic book and an award program.

A trademark for a tobacco product is in a completely different category than bathrobes. If someone attempted to pass off a trademark obtained for a tobacco product for cannabis or a cannabis product, or a bathrobe, it wouldn't be recognized in court, because it isn't represented by the correct category.

Cannabis, if it were legal, would have it's own unique TM category. But, as of this date cannabis is not a legal product, so there is not a TM category to register a name.

Reminder, don't believe everything you read on the www.