I've never tried one and never been interested in one...until you mentioned 'machine washable'.
That being said, seeing online recently different suggestions as regards keeping warm I realised I'd become very remiss on something. Over the years, I'd got into the habit of wearing plastic slip-on shoes (single bar) round the house and then wearing them without socks. I've recently made the effort always to wear socks and bought some cheap fluffy slip-ons that were under £3. I'd forgotten how much warmer they are.
So whether or not I buy a heated blanket, you've given me a very, very timely nudge to give more thought to the whole staying warm thing.
That being said, I thought recently how I don't do enough housework and reminded myself that it's exercise and also that I find it soothing. This thread has now given me a further motive as I've remembered that it can be warming as well. Obviously, not everyone is physically able to be pottering round the house cleaning and tidying, but you'll have noticed how I mesh ideas together in my head, one idea prompting another.
Thank you.