I've been teaching myself to paint with acrylic and am putting together a portfolio with the goal of one day selling my work. A few pieces have received very positive feedback and I would like to include them in my portfolio. My problem is that paint has leaked or streaked onto the back of the canvas. I tried wiping the stains off with soapy water but wasn't able to remove them completely. I finally painted them over with white paint, but it's an obvious cover-up. Will this hurt my ability to sell them at a future time? Thank you for any advice you can provide.