Greg- it would work and would be safe from a shock/OCP perspective, but it's a terrible design, one that would lead to nuissance trips, and one I'd certainly never put my stamp on. Seems from this discussion that the legality is a gray area, depending on how the AHJ interperets a couple codes. I really can't see anyone ever approving something like this. Was an interesting discussion, though.
djk- The issue for the washing machines was probably the motor. 50Hz DC rectifiers work great at 60Hz, better than at 50Hz (the reverse is not true), so electronics shouldn't be impacted. Tuned harmonic filters could be an issue, but they're not very common in appliances. Transformers may heat up a little more if the plate laminations were designed for 50Hz, as 60Hz needs thinner laminations to mitigate hysterisis losses, but it would be a fairly small heat gain- not like the fire you'd start if you put a 60Hz transformer on 50Hz and saturated the core.
The big problem I see for a 50Hz washer on 60Hz power would be syncronous AC motors. If they're designed to work at 50Hz, they'll spin 20% too fast at 60Hz, and I can see that causing quite a few issues in washing machines, food processors, etc.
