Re: So-called "smart" spackling dries rubbery
Never heard of that particular product, and am not sure why you'd be smearing a spackle material on your walls when that is not what it is used for. If you're trying to skim coat walls, you use drywall compound or topping compound, topping compound being the better of the two because it is smoother and easier to sand when dry.
As for getting it off the wall, I would recommend checking the manufacturer's website for cleaning up dried material and possibly some troubleshooting guides on why it has become rubbery. I would probably even go so far as to contact the company for help if you don't get anywhere with their website.
What you're probably going to end up doing is to skim over the top of the spackle with drywall topping compound to get rid of the sticky and have a wall you can work with.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!