I notice that there are loads of waterproof silicon shoe covers being sold online, have you ever bought a pair? If so, are they any good? Some are advertised as low has £7 a pair, including postage.
When I go camping I can think of two occasions when they might be useful? Not to use as shoe covers but to just slip on when, a) I wander from my tent to the shower area and back again b) if camping on grass, to slip them on when I get up in the morning and then, when ready, put on my socks and boots and c) to slip on if I have to get up and wander over to the toilet block in the night?
I don't think I would ever use them to slip over my boots or running shoes on a normal walking or running day unless of course I was kind to the proprietor and slipped then on when I wandered into a cafe or pub on a wet day?
I normally carry a pair of flip flops or lightweight shoes so if this is a good idea its also a weight saver as well.