One of the first rules I learned when I started to design was to never horizontally or vertically stretch type. I've never had a problem with this rule since the results were so terrible looking I couldn't see why anyone would stretch type in the first place. Last week I heard yet another reason why stretching type is a terrible idea. During Ed Benguiat's class he had a print out of some large sans serif type and had us look at it normally and then turn it 90 degrees and look at the same letters again. Turning the paper revealed the slight difference in the thickness between the vertical and horizontal elements that wasn't apparent at a normal reading angle. The horizontals were always just slightly thinner than the verticals, and it's this slight difference that keeps the forms feeling balanced. Even Futura, a geometric sans serif that one might expect to have a perfect uniformly stroked letter "o" was designed with this balance in mind. So here's yet one more reason why you should never stretch type, not even a little bit. When you stretch the type it causes the horizontals (or verticals) to thicken and destroys the intended visual balance.