Prep makes all the difference.
I actually sanded the whole inside of the tub down with 400 grit and was going to paint it body color.
My wife said don't make the inside shiny because I would freak out when our 5 yr old granddaughter puts a scratch on it.
I though about it for a day or so, and sanded it down with 80 grit and shot bed-liner on the inside.