I'm not sure exactly what you were told, but projecting off axis (not being perpendicularly centered) is very undesirable for projection. Certainly, the more modern projectors have options like
lens shift and digital
keystone correction which gives you the ability to reorient your
image, but at cost to quality of your
image (in the case of digital correction). We have talked about this in a few of the other threads. Essentially when you are not projecting directly on to the
screen, light does what it does and creates a
keystone effect. With some projectors, you can get as far as 35 degrees off of the perpendicular axis and have the
projector reshape your
image so that it appears to fill your projection surface correctly. This of course does not correct for the light being projected and so you will lose the even brightness over the surface of the
image (the smaller portion of the
keystone will be brighter than the larger portion).
In some of the arenas, I have seen mirror units (by
High End Systems ) that attach to the front of some of the large frame projectors so that they can sit horizontal and project down onto the floor. Essentially it makes your
projector into a moving light similar to adding the
Rosco iCue to a Source-4.
What situation are you facing with your projection? Maybe if you give us some more details, we can help you find a solution.