Even after decades in the hobby, I still don't like dealing with concierge's. My usual tactic is to get in the area 5 - 10 minutes early - text the agency or SP to see if everything is still on schedule. Get a specific time to buzz - then after I am let in, I just walk purposefully to the elevator (make sure you know where these are). If you look like you know where you are going - most concierge's in the condo's which have incalls won't bother you. The few times I've been stopped I have only had to sign in - no questions - so you put your fake name and time down and carry on.
In my experience, most incall condo's are at condo's with a high rental rate (vs owners) and thus a high tenant turnover rate. The concierge's are really there for deliveries, service calls, etc - not to aggressively screen visitors. In this type of building, it's not like the concierge knows all the tenants. I have to admit that concierge's always make me a little nervous though... I guess this adds to the excitement!