My problem with my knives in the dishwasher is when the family tosses a shaving sharp kitchen knife in with the bowls up top... good bye shaving edge, hello toothpick dull. I yelled enough times that now my kitchen knives get put on the top of the sink and washed by hand. Kinda helped when I refused to sharpen thier butcher knife again until they quit tossing it in loose
If you can keep other stuff from banging into your edge, you solve that problem.
The big reason ppl say not to wash kitchen knives is because of handles. The good old high carbon knives usually had wood handles, and the dishwasher will let em rot over time. With the new nylon or kraton ones, you don't have to worry.
As far as "how many times"... I haven't found a limit yet
I toss my spydies(closed) into an open cutlery section, and then lube em up after. I prefer washing by hand with HOT tap water simply for speed, but have tossed em through a load for convenience a [i[few[/i] times. Dish soap (the liquid stuff for the sink) is good for your knife. Get your knife wet, get it soapy, rinse it off with hot tap water and shake it dry... lube it up. Dishwasher soap(usually powder) is corrosive in nature and will eventually make a mess of your blades(just look at a drinking glass after 40-50 loads). If you use liquid stuff in your dishwasher it doesn't do that