I use brake fluid (the cheap stuff from WallyWorld).
I got a big aluminum pan, brush on the brake fluid, let it set a few days, brush on more as needed, scrub off with a scrubby kitchen sponge & it comes off pretty well.
Wet sand down from 220 to 800 grit, wash in the sink, wipe down 2 or 3 times with rubbing alcohol & it's ready for paint.
I did Clinton's bezel this way & it turned out pretty well.
I might have to try the spic n span though.