Disclaimer: This is my experience. Yours could be different! We crossed yesterday at Nogales. No, They did not take all my meat. Nor did they shove a rectal thermometer into our Kitty. No checking...
nogales has a lot of advantages. I had one problem last year when they would not allow my ATV because it had permanent plates (none expiring). A visit to the aduana fixed that. I wa smart enough to copy his permission slip before handing it over to banjercito.