There certainly does seem to be a wide variance in the properties that Hilton is willing to allow to carry its brand. To call some "substandard" would actually be letting them get off easy.
An example: The Hilton Embassy Row in Washington, DC. This is a property that took the Hilton name not more than a year or two ago, but quite obviously did not undergo a refurbishment in the process. On a recent stay I found the rooms speck-sized, the curtains soiled and torn, and the carpet worn thread bare. And that's only what was apparent in the first five seconds in the room. The worst part was the leak that developed from an antique heating system in the ceiling, sending a gush of water down at about 1:15am and continuing to drip until I finally requested to be moved in the middle of the night so I could sleep. The property markets its charming Colonial style - what they don't tell you is that it truly is some sort of Colonial relic! The service is decent, but doesn't have much to work with.
Being a lowly holder of a purple card, I can't really speak well to its adherence to the elite levels of the HHonors program, but I can say that a Diamond-level colleague travelling with me did not have a much better experience than I did. To get a room larger than the standard speck-size (something approaching shoebox), he had to move down from the premium floor. Not that he was missing all that much - the selections in its lounge were meager, and the business services nearly non-existent.
All in all, not one for ol' Conrad to be very proud of, in the Moose's opinion.