I did a lot of BookFunnel promos last year because they were free and held the promise of using narrowly targeted categories. Unfortunately, BookFunnel refuses to change its categories and includes "active erotica" (what the heck is that?) in "romance," so unless the person doing the promo made it very clear that this was "clean, sweet only," some skeevy covers showed up. I didn't want to promote them to my list, but the only way to know if such covers were going to show up was to check what the promoter posted, and sometimes that info was not available. Also, often there was no simple way to access a promo graphic and I had to email to ask for it. Time wasters.
Aside from promoting to my newsletter, my only social media is Facebook and I could tell that FB was suppressing all my author page posts. (My profile page is mostly read by a non-romance-reading audience.) So I felt I wasn't helping the promos much since my list wasn't going to buy sexy romances and my FB notices were being suppressed. The whole point of doing these promos was to promote without paying for ads, so of course I wasn't going to boost my FB posts.
All that, and the promos were not selling my books. It was worth a try and I did it for many months, but in my opinion for me it was a failure. I didn't particularly like letting down the promoters, either, with my lack of fabulous media reach. The increasing threats from some promoters weren't much fun, either, even though my share score was decent enough.