Not acknowledging known issues is pretty standard fair with the store employees. I have talked to a few that go outside of the box and are willing to help because they know there is a problem (clearly they have a conscious) .
When I purchased my Galaxy Nexus I realized immediately there was a connectivity issue and extremely poor battery life. Went online and found the problems were rampant. I went to a local store and everyone feigned surprise, "No, never heard of the issue before". One manager grabbed me and pulled me aside, she said that it was known issue (she had a Nexus for a short time) and proceeded to get me in to a different phone.
On a different occasion I was playing with a demo version of another phone I owned (Droid Bionic), I saw that someone loaded Speed Test so I ran it. The score was more than twice what I ever achieved with mine (mid to high 40's, hit 50 one time in a store, best outside of a store was 38, average of 24). So I ran mine in the store....it duplicated the results of the demo unit. I asked the store employee if they use a booster and he said no. I showed him my Speed Test results and he said that they were very close to a tower...(LOL).....since then I always run a Speed Test while in a store, always incredible results (doesn't matter what store). Makes sense, Verizon wants their devices to work blazing fast in the store(s). Yet you will never get anyone to admit that they use boosters.
It's a business folks, they exist to make as much money as they possibly can (even if it means the occasional lie).
Currently the GS3 on Verizon has known issues (I say that with tongue in cheek) with their GPS. I went through 3 before I finally gave up. Talked to 5 or 6 different techs and they all were not aware of an issue. Finally one tech acknowledged that there is an issue and Version is fighting with Samsung to fix it. She said in good consciousness she could not send me another GS3, that's how I got into the DNA. Less than a month old but have never encountered an issue with the SIM card....maybe I got one after the fix???