Honestly, posting smut is IMO the most nerve racking thing, whether it’s a smutty moment in an epic, or a oneshot where everyone is naked from beginning to end. Writing smut is fun, but posting it still scares the shit out of me, tbqh, and I say that as someone who has nearly 50 stories of some flavour of smut, MM, FM, and FF posted (which I’m sure isn’t a record, but I’m hardly a newbie at this point), and loads waiting to be posted that I’ve tried out on friends.
I still get nervous, I’m still paranoid until someone comments (and sometimes even after). I am still terrified when I post for a new pairing or just when I post something I haven’t posted before. It feels like you’re taking something very personal and making it public, and it’s a relief when people comment and say it works. Conversely, if no one comments, there’s a little voice in my head saying “They hate it” or worse, “They hate you/think you’re weird/twisted/oh my God, no one else thinks this is hot/sexy/sweet/romantic.”
I know it can feel weird commenting on smut, but for similar reasons, that’s when your pet fic writer really, really needs your feedback and will be relieved by it. I don’t suppose everyone is as paranoid as me 😉 but otoh, I am sure I’m not the only one who has to resist the temptation to bite my nails to the quick until someone comments, or who reloads and checks my mail compulsively, hoping for comments or at least kudos. However strange you might feel saying “It was really hot when…” the writer feels a hundred times more exposed and awkward, and your comments mean a hell of a lot.
NB: That doesn’t mean you have to (or even should) be explicit. Say something works; you don’t have to tell me it made your genitals tingle… just to be clear!
So yeah. Honestly, much as I adore the people who write coherent reviews, trust me, a gif, a keysmash, a “holy hell that was hot”/“I’ll be in my bunk”/“I was reading in public and had to close to page” type review? I treasure ‘em. I think we all do. Any of those is an absolutely perfect response to smut which will reassure the writer and let us know we… um… hit the spot. God, everything I write here will sound wrong so imma stop while I’m not quite in the gutter.
TL;DR: Writing smut and letting it out into the world is even more scary than reviewing it. Please be kind to your fanwriters, especially when they have given you delicious smut to enjoy.