I tried this recently on a LIGHT stain on my mattress. I wouldn't think it would work on a deep, soaking stain.
If you have a light stain, try using one of those Clorox wipes on it. For me, it lifted the stain. It was wet enough to do the job but not so wet as to drench the mattress. It did not alter the color of the mattress. In fact, I ended up running it over the complete top of the mattress and it freshened the entire bed and dried very quickly.
We were given two hands to hold, two eyes to see, two ears to listen & two legs to walk. But why were we given only one heart?
The other heart was given to another for us to find.