I don't respond under the assumption that the recruiters are sending hundreds of messages and really only care about responses from people who are interested. I

I don't respond under the assumption that the recruiters are sending hundreds of messages and really only care about responses from people who are interested. I assume my lack of response won't be noticed and that notifying them I'm not interested only creates more distraction for them. Also, I never accept connection requests from recruiters. The reason they normally request to connect is because with that request is the only way to deliver a message for free (and after they're connected they can message you forever). And I like my contact list to be only people relevant to me--it's nice to scan my contacts occasionally and see where people are working now, and to see status updates from only people I care about.