A few young authors did ask me to read and review. I usually go and read, and, if I liked it, I review. However, if I didn't like it, I usually stay silent. Because, I really not sure that I'm entitled to judge. Cheerlead - yes, give an advice - sure, no problem. That said, a few times I was coaxed into giving my thoughts about controversial stories. In those cases, I wrote a gentle PM with my concerns directly to the author. I think, in the end, I worried more than authors themselves. Haha!
There were a few occasions when I voluntarily offered advice. But, it was about the use of Russian classics or Russian language.
I don't have a lot of bad reviews. I am not big or bright enough to attract that kind of people, aka trolls or haters. Just a few stupid remarks. They usually get something snappy from me. Well, as snappy as I can manage anyway.