I was playing with the MTM1 <a href=http://cownap.com/~mtmg/models/Mtm1/Mtm1pics/camptrlr.jpg>Camping Trailer</a> (<a href=http://cownap.com/~mtmg/models/Mtm1/vehical1.html>here</a>) in Binedit and noticed strange things. For one thing, after I edited the model and saved it - the next time I opened it it would fail to load, giving an "invalid face type" error, consistantly. I fixed this however, by selecting all faces and setting the group face type to normal before saving the model, so this is a trick to keep in mind if that error ever shows up again.
Also, notice the black hitch on the trailer? Oddly it isn't mapped to a black area of a texture, it's just mapped to a sort of squashed nothing at the edge of a texture, or something. It's odd, this screwy mapping results in that coal black color, you could normalize the model to any texture you like and it would look the same (I think).