We are all guilty of it, blowing on our carts to get them to work. Here is a great article about why you shouldn’t. I use alcohol and q-tips to clean my carts with great results. If that doesn’t work I will take the cart apart and use an eraser on the contacts.
So, dear readers, all signs point to no: blowing in the cartridge did not help. My money is on the blowing thing being a pure placebo, offering the user just another chance at getting a good connection. The problems with Nintendo’s connector system are well-documented, and most of them are mechanical — they just wore out faster than expected.
Having said that, it’s true that kids can be grubby, and getting crud into the cartridge or slot was a real problem — I suspect that most of that crud was not just dust, though, and required a more thorough cleaning than a moist mouth-blast could provide. In fact, Nintendo released an official NES Cleaning Kit in 1989 in an attempt to keep both the slot and cartridges clean. Ultimately, Nintendo redesigned the NES console, releasing an NES 2 console in 1993 that’s commonly known as the “top loader.” Its main feature? A top loading slot. It was more like the original Famicom, using a slot that held up better to abuse. Similarly, the SNES (Super Nintendo Entertainment System) was a top loader.