You know what the secret is about "blowing" and I don't want to say it since it is a horrible secret which I do not commit to
While yes I do agree that blowing directly on a cart will make saliva get on it and thus sed damage the cart but not as much as alcohol.
However the thing is....
I rarely blow into cardtridges. I used to do it a lot when I was young, until a guy at a video games store told me that I could damage the game.
I'm using rubbing alcohol and cotton swabs, since. Besides, I'm always keeping a small bottle filled with rubbing alcohol and swabs, in my games cupboard.
I like to take good care of my games, there's dust cover on all of them.
I'm a real game geek!