It takes mark a closer look to find an irregularity in the array of matrix icons. There are a lot of commlinks around here, which doesn't come as much of a surprise given that you are in a hotel. An inspection, however, shows that one guest is using a Hermes Ikon, which is considerably better than the gear other guests use in this shabby hotel.
No other sign indicates that your man could be found in this hotel. Until Scarcrow directly asks for the drug dealer.
"Weasel? No, I do- Oh! Yeah, yeah, you mean, you want to go to room two-oh-four, right? Is that it?"
The receptionist, obviously an inch less professional than the Weasel would wish for, explains you the way to the room in the second floor. A second look shows Mark that this is the room where the more expensive commlink is being used (currently in full VR mode, by the way).
Before you even find the time to knock, Scarcrow and Cinder are being sent a message: "Who are you?"