You know those small ones you see Target, Dollar Tree, etc. that come with maybe a nail file, toe separators for a manicure, etc. I keep one on my laundry shelf. When I get a stain, I spray it with a good spray (I only use Shout Advanced gel, nothing else works for me) and I scrub it with the manicure brush. It has the little handles so it's easy to hold on to and much better IMO than the stain removers with the bristle brushes attached. IMO they are too soft, these really can give the stain a good scrub. Things I have given up on I tried with the brush and have been able to get the stain out.
One word of warning, mine got icky after awhile (maybe 3 months) and I threw it in the washing machine. Well it broke, so I wouldn't do that again. It's a great way to repurpose those little brushes if you have one too many. I actually seek them out when I'm at Target, I also use the clippers in the set (they truly are too poor really to cut fingernails) to cut tags off clothing. Sometimes I'm searching high and lo for scissors, but 'somehow' no one needs nail clippers, bad ones at that. So they don't wander off.