Noticing that people replying to other people I don't follow are showing up in my local timeline. So now I'm worrying: every time I have a conversation with someone, am I polluting everyone else's timeline with an unending series of replies?

That was one thing "the bird site" got right: you didn't see peoples' replies to people unless you followed both of them.

@csilverman you can set it so only the people you mentioned can see it (or set it to private, in which case you can set it so only followers can see it)
@kuro heh, just had that pointed out to me. Good to know.
@csilverman yep, replies show up in home, but not in federated timeline.
@csilverman you are not, my friend. Unless they make the reply public, as I just did. 😬
@csilverman Only if they're using the Federated timeline. They can always choose not to use it.
@csilverman Amarok gets this right. Replies are unlisted by default. I think it's just the web interface that defaults to public for replies.
@pete @csilverman The usual opinion on this here is that this is a good thing, as it makes it easier to jump in to other people's discussions and thus encourages conversation.
@lambadalambda @csilverman Thank you. I keep forgetting that mastodon and GNU social have been around for a looooooong time and of course all of this has been thought out and debated.
@pete @csilverman At least on GS there is a setting in the frontend where you can hide replies, but the default is the other behavior.
@lambadalambda @csilverman @pete it's also how birdsite used to be. hiding replies was a later change.
@evilchili @pete @lambadalambda @csilverman On birdsite, go to Notifications --> Settings --> Turn of Quality Filter, to see what it used to be like (for the most-part).

@lambadalambda @pete I'd generally agree, although I'm still trying to get a sense for how accepted that is on here. I've replied to a few people and gotten sort of a "wtf where did you come from" reaction—maybe some people aren't used to that, or don't really like it.

Which is why I was worrying that other people were seeing their timelines fill up with my replies and thinking "jesus, asshole, shut the hell up and let someone else talk for a change".