@s55 sir you are seriously misguided by the channels you view / listen to
the arrivals' gate connected to aircraft are CCTV covered, The Central immigration & homeland security office located somewhere in the building can remotely TAG any passenger from anywhere between arrival gate onwards, can be flushed out for screening by an immigration supervisor prior to immigration counter.
allow me to ask what is making you so confused / irritated / unsure about taking a journey to USA despite having a visa. I can see from the question pattern you have asked over the period of time. You want to visit the US, and at the same time you have a doubt that you may not get an entry, may get declined at port of entry. ?
why you are so scared ? do you plan to dodge and slipaway for good after landing. just a wild card guess
Trust me this does not work anymore specially after bio-metric / eye pattern data on immigration / visa application.
take the flight take the entry enjoy your trip, if entry is declined , to hell with US, whats the big deal with Amreeka man ??