Reruns are fine. Heck, one of my favorite shows, In The Heat of The Night, I never even knew about until a few years ago; over a decade after new episodes ceased.
I also catch Frasier and Cheers every morning; one of the local channels airs them.
I think the thing with reruns is to avoid them of a certain show until it's been long enough you've forgot most of said show. Then it's once again top notch entertainment for you. I also frequently catch shows I love now that I disliked then (Friends for example; no clue why I hated it back in the 90s, it's funny as hell I think) but, unfortunately, there's also the few shows that just aren't as good as I remembered them being.