Wait, are you saying there’s a guard near the elevators in the tower or just the lobby? Also are you sure he’s checking ID’s? Not just making sure you have a room key? If they’re checking actual ID on the room floors I want to know where you are.
Anyways even if he remembers you and remembers that he saw you with a different woman the day before he won’t care. Nobody in Vegas gives a fuck unless you’re raising a ruckus.
As LaRue said, you meet her downstairs and go back to your room with a beautiful woman on your arm. Unless you’re on a trip with other people you know who are in the hotel this shouldn’t be a problem. I’ve done this in Vegas hotels with small quiet lobbies and no casino. No blending in with the crowd. Maybe somebody guessed what was going on (doubtful) but truly nobody cares!
If they are in fact well reviewed and if they’ve been in Vegas for a good amount of time, then they’re familiar with the hotels. Let them tell you how you’re going to meet up and get to the room. You’ll be fine.
Avoiding stings is part of why you’re seeing well reviewed providers. LE is not walking up to random couples in public asking them their business to try and bust providers. Not yet anyway.
I’ve never heard of LE asking for a deposit. Same with screening. Did they want screening info? You could theoretically lose some deposit money (unlikely if she’s well reviewed), but from everything you’ve said it’s wildly unlikely you’re mixed up in a sting.
As to the last line of your OP, there is always risk. We do things to minimize risk but there is always risk and each individual needs to decide what level of risk they are comfortable with. There is risk of arrest, being caught by an SO, getting ripped off, risk of STI and so on. If you want zero risk you’re in the wrong place (planet earth).
If you and your lady friend are both sane adults with common sense, your risk from the guard is very very minimal. If you have your key and she’s obviously with you, you will be fine, provided you’re not screaming at each other or having sex in the lobby.