Prep work is the key to anything like that. The person who did the bed liner, likely cut corners on the prep work and now you are left with the mess. Do you want to paint it the original red color? If so then you will need to get all the bed liner out, then sand and prime the metal. If you want the bed liner as well there are tons of threads here about that and make sure to take your time when doing the prep work to put it on. Hope that helps.