A simple and probably stupid question: Though I installed a 'permanent' style AC filter in my home AC I forgot to 'clean' for 2 months---will this cause the fan motor to clog up or burn out?:confused:

It depends on how much lint and dust the filter is catching. If after a month you don't really see any build up on the filter then you leave it for another month, still if it is not really dirty you can take it out and dust it off and it should be good for at least maybe three months. Now it is another story if after a month you take the filter out and hold it up to a light and can't see through it very well then you should clean it every month.
There is a way that a dirty filter can help burn out a motor. As the filter gets dirty the fan runs faster, the faster it runs the more amps it will pull therefore damaging the motor.

Very well put letmetellu. There is a reason they say that the number one maintinance on a furnace/ac is to check your filter often