I never sample either, that would ruin the book for me. I realize some people find it useful, but not me.
I have around 550 books on my tbr list on GR, everything from fantasy of 19th century to yet to be released books. I don't need to sample, I know exactly what I want to read. My only problem is what to buy first from that list

I'm also surrounded by a big group of primarily fantasy readers so if I see them enjoying a book, chances are I'll try it too. I know which of them have similar taste to me.