What j123 said. In MT your are not "allowed" to trip, throw your opponent. If he fell down, it must be because he lost his balance after one of your strikes.
Obviously it's a lot harder to clearly tell the difference between a trip and a strike... Was it a knee strike to his thigh while clinching, or was it a trip with the knee. Was it a kick to his ankle, or again just a trip...
But it's something you are taught and train, because loosing balance in a MT match, scores points for the opponents and makes him look more aggressive. It also sap your confidence, and drain your energy.
I believe a judoka would have a clear advantage, but a MT clinch is a lot tougher to deal with than most grapplers expect it to be.