I have not seen in person one of these rolled Animal House one sheets that is on a different kind of paper. I have seen several that are on the "right" kind. However, even if it is on a different kind of paper I wouldn't be so quick to immediately classify it as a reprint/commercial poster. Maybe it is just a different printing. We all know that posters from that era were often printed at more than one location. If it is a full size 27x41 (or within 1/8" of that), in my opinion it stands a better chance of being authentic than it does of being a reprint. Most (not all) reprints are usually significantly undersized.
I have probably had about 10 or so rolled ones over the years. All have been on the same kind of paper. Never seen one that felt different or stood out.
That being said.....If the print QUALITY is different, and if the paper is super minty white and it smells funny... then I would be very suspicious.
I remember being at the hollywood collectors show several years ago and this lady dealer had a "the sting" one sheet, flat never folded shrink wrapped on foam core for sale. Even though it was shrink wrapped I could tell it wasn't the right kind of paper. I took out my tape measure and it was 27x40. She got very angry with me when I politely suggested it was a reprint.
We have posters shipped to us all the time. Every now and then we will get in something that just doesn't feel or look right. It is almost always very easy to tell if something is a reprint.
As for the whole paper test thing......I think it is flawed. Don't get me wrong. MPGrading is great and Todd Spoor is doing great things for the hobby, I just do not think their scientific tests are 100% accurate.
