Originally Posted by LumensLover
Keystone is terrible. Stay away from it at all costs if possible.
Lumens is a little prone to hyperbole.
Most AV enthusiasts will avoid using keystone correction as using it reduces resolution and can cause artifacts that will become more noticeable the more correction you apply. I always recommend to avoid it when possible but then I’m an OCD AVS forum member that scrutinizes every little detail to maximize my AV experience. While I don’t use keystone in my home theater we have a projector set up in our bedroom that has some MILD keystone correction applied and even with test patterns it’s nearly impossible to tell. Again: if you can avoid it than do so but if you can’t it’s not the end of the world.
What to do if you find yourself stuck with no hope of rescue:
Consider yourself lucky that life has been good to you so far. Alternatively, if life hasn't been good to you so far, which given your present circumstances seems to be more likely, consider yourself lucky that it won't be troubling you much longer...
-- Excerpt from the Hitchhiker's Guide to the Galaxy.