You can roll, that's fine. But if you're just "Doing a scan of the room," you will only ever notice something that OBVIOUSLY is out of place or unusual. You're not going to notice a hidden door or a shady handshake covering up a hidden message being passed if you're just scanning the room, no? So if you don't specify that you're looking for something in particular, then why would you notice it if it's subtle and sneaky? You wouldn't. So, no matter how well you roll, you will never see it. You only see it if A) you're specifically looking for it, and B)  If you have a REASON to look for it or notice it. If you're not looking for something like discrepancies in armour, why the fuck would you notice it from across a crowded, noisy bar? You won't see it if you're not specifically looking for it, because why would you?<br/>Also, recognising crests would require a Knowledge Check, but I get your example.<br/><br/>In any case, small details like crests and the like are unlikely to be found in a "Scan."<br/><br/>Now, you CAN roll for a "Scan of the bar," sure. Just don't expect to find anything all that earth shaking, since you're just doing a cursory scan and obviously wouldn't inspect anything in particular for that long...if you were, you would have specified it.