"Scrubba", but we haven't tried it. It looks like a neat way of hand washing without all the splashing, although we could probably simulate this in a hiking dry bag without spending the money.)
When we do need a washing machine we have found four main options: campsite machines, commercial launderettes and 24/7 launderette stations that we discovered in some French supermarkets. The machines we have tried on campsites tend to be just like the machines in private homes, quite small (5-6kg) and well used. Some of them have really been quite grotty and haven't really given a good wash. They can also be quite expensive. On the plus side they are close to the motorhome and we can relax while the washing gets done. Commercial launderettes usually have much bigger, better machines that can take a lot more washing, seem to give better results and, on the whole, seem a more cost effective option to us. However, it does mean taking our washing to one and often waiting around which can feel like we're wasting our day.
A fourth option that we used in some mountain ski resorts was that property management companies who look after people's apartments seem to have their own washing machines and often let people use them for a fee, either doing the laundry for you or letting you access the machines. Prices are massively varied though. In Grimentz we did 5 small loads for less than £10, but in Zinal the company wanted the equivalent of £15 to do one load!
Doing laundry in the motorhome might seem like a bit of a hassle, but we certainly haven't felt that way. Occasionally having 'chores' to do is one of the things that makes the difference between full time motorhome touring and being on a shorter holiday and we've even find the normality and routine jobs make us appreciate the adventure even more.