I think it is important to use these sparingly, even if you find them a good source, simply because you don't want to present the image of getting your sermons from the funny paper. Also, don't copy them without expressed permission from the author. Rather, just describe them. Movies and Television Programs Caution is urged here. Much of what is on TV is not fit for Christian consumption.
Many movies are the same or worse.
Of particular note regarding TV are the evening sitcoms that constantly mock morality and decency and make joke of things God says are serious matters. A preacher's quote from such a dubious source can sound like an endorsement. I seldom utilize this source, which probably stems from the fact that I don't watch them. I mention it here because there is probably a place for some careful gleaning, if only to illustrate the wrong way of doing things. Radio Radio can be a good source of illustrations.