A hacked or bought account that will post nsfw links all around youtube mostly in popular youtuberscomment section nsfw linkers usualy steal comments but they also spam original comments you can spot them by their bios, usernames and pfp for example:
"Go to hot_babes696969.com to find sexy ladies"
The pfp's are also usualy a dead give away being a lady in a bikini having her boobs show or her ass
The username could be go to my bio to have sex and the bio could be a link
"I've found some nsfw linkers in the comment section if you find them dont click the link"