I have family (aunts and uncles and such) that live in mexico, so i go down there a lot just to visit. every time that i have been across and back (maybe 20 times) we have never been searched. usually we carry a bunch of trinkets/presents back with us, so the guards can usually tell we are tourists and just look through the shit in the back. however, we drive a big conversion van, and even then, they have never done anymore searching than just through junk in the trunk (ha!). i myself have never smuggled simply because i don't want to put my family at risk, and because i haven't done a cycle yet
however, let me tell you this little story... my dad went into mexico to pick up some of our family and bring them into the states for a couple weeks. they were not smuggling anything, they were not suspicious-looking, they looked like perfectly decent people. unfortunately, the border patrol guard they ended up with was having a bad day or some shit, because he had my the entire group my dad was driving strip searched (orifices and all) for no reason, and they also turned the car upside down trying to find something to pin on them, but they found nothing. even though this happened 20-ish years ago, i tell you this because even if you don't look suspicious, that won't guarantee that you won't have a bad day at the border.
by the way, it might be worth the extra trouble to go down a little deeper into mexico to get your stuff, simply because i know how shady the people living in border towns can be. i've had a couple bad experiences that have convinced me to not even stop to piss in a border town. good luck.
peace
the shocker