Making customs declarations when entering Mexico

We have had a red light a couple of times and they do a quick walk through and your done. They have open a cupboard or two at times as well. Lately I have heard from a friend who had a friend of a friend got his meat seized at the boarder. Another had their beef only seized. We asked about this and they told us there is no problem with meat brought into Mexico by a RV'er. I have not had a chance to peruse these stories any further as they will not apply to me till next season.