I typically don't ghost-- the only reason I've ever ghosted someone is because I stop being interested in roleplaying all together and disappear from the site/discord server I'm roleplaying on for a while. But I dodge messages all the time because it seems to be a common thing here, especially, where people either don't read request threads or message with an idea that's so banal and obviously driven towards a one shot smut fest that I just don't even bother to reply most of the time. I've gotten messages where it's like "Would you like to play one of my lovely ladies?" And that just grinds my gears, let me tell ya.
I don't mind if people direct me to their request thread if it's to do with discussing plot, especially if they say "Would you consider checking out this idea for our roleplay?" Because sure, I'm down to consider the ideas they've already come up with, and there's no point in them rehashing their concept if they've already written it. But if they come to me specifically to say "check out my request thread" I just ignore that too, because... why would I? I look at the request threads all the time, if yours didn't catch my eye in the first place, why would being DIRECTED to it do any different?
If I'm feeling in the mood to put up with a conversation, I'll tell the person that they obviously didn't look up my thread/interests, and point out the fact that what they're asking me for doesn't appeal to me, but most of the time I'm not interested in wasting my energy on that back and forth, because people who message me to get a specific kink I have no interest in, ask me to do a plot they came up with with no consideration for my own interests, or who type next to nothing to catch my interest are at least to me, clearly not going to be inventive and interesting roleplay partners in the first place.