They work but why pay for it? Clear a spot under an overhanging branch, maybe beat the branch up a little, piss in the scrape, and walk away. The only thing you might need to buy is some type of licking branch scent. I usually don't have any of that with me and they still work almost all the time.
I've had a lot of success doing this... I just scrape an area out with my boot with a branch over head - then I pee in it every time I pass it up. I get great videos leading up to the rut.
Not against the store bought stuff but no way I'd pay for it when I can use my own pee. If I find a scrape I'll hold it until I'm finished hunting just to pee in the scrape.
I know where most of the community scrapes are or whatever you want to call them that are in the same spot every year. I was home in October and they had yet to start it there. So i started it for them and came back the next weekend and it was tore to pieces.