For me, the dishwasher method is a method of last resort. I do it after I've tried all the usual things and failed. And only after a visual inspection reveals that goop has afflicted the board. So, really, what have you got to lose?
Whether or not you intend to re-cap, a thorough clean is a necessary first step. You can choose the dishwasher method, or a point-by-point clean with a cotton swab and alcohol, or any number of other methods. All of these will wet the board, requiring a thorough rinse and dry.
My own personal experience with this procedure is that, if you do it carefully, the clean will only make things better. Without recapping, I've seen closer to 80-90% success at getting it to boot (that's based on perhaps a dozen boards). My laziness prevented me from going further with the remaining couple of boards, but I strongly suspect that recapping would have brought at least one of those back to life. [And recapping is necessary for a reliable job in any case.]
If you choose the dishwasher method, just pull out any socketed things that you can readily remove (ram), and allow the board to dry very thoroughly before re-applying power. This latter step takes time, and impatient folks often rush it.
Again, if you've tried all the "normal" fixes without joy, you've got little to lose by washing the board. I only see potential upside.