I recently purchased the Perfectly Placed Guides as I was experiencing the same problem. I put the stickers on a few of my first sets and then stopped as they weren't sticking. Its only been a few days but so far so good. I did wash all my blocks first using the blue Dawn dishwashing liquid (I read that tip on SCS). My guides cling to the blocks just fine. The stamps also cling even when cleaning in the stampin' scrub.
I did not want to start applying any type of glue to my stamps so I thought I would try this first and I am very happy I did. You can use clear vinyl but the guides also have lines on them so you can get double usage out of them should you need help lining something up.