Back in the old days of the interwebbings, when HTML tags had their own set of rigid style elements and the closest thing to dynamic content was regularly and manually uploading fresh versions of your site to your webhost, there was such a thing that the masses saw fit to name "netiquette". It's an awful portmanteau. However it was a largely unwritten set of rules by which participants in a virtual social group were expected to conduct themselves.
There is still an etiquette to the use of social media on the net, and for the most part it's just a matter of showing a little consideration for those who are following/friends of/subscribers to your feed/wall/blog. There are however some common infractions of this social agreement and a couple in particular bug me.
I realise that I am a grumpy old man, but I'm making no apologies!
One is the mirror-only feed. This is the twitter (or similar) feed that only carries notifications that one of your other feeds has been updated and contains no original content of it's own. While I fully understand your use of twitter to promote your blog, if it's your only use of twitter then I get the same value from your blog's RSS feed already. These are the twitter accounts I'm most likely to get bored of and unfollow. Twitter is an excellent platform for smaller exchanges and broadcasts, make better use of it! I can be forgiving of a single feed that aggregates numerous services that you use into one coherent stream, but pick a service with RSS rather than twitter.
The other particularly irksome habit is the prolific photostream spammer. These are the promiscuous instagram (or whatever) accounts that drop a batch of 20 markedly similar images onto their feed at once, pushing everyone else's contributions one or even two pages back. Edit! For the love of His Noodly Appendage, EDIT! Pick your best one or two images and show them off alone so that I can appreciate the contributions of the other people I elected to subscribe to but also so that I can appreciate the cream of your efforts better too. A service such as Flickr is much more appropriate for gallery-sized dumps of images. I probably agree that they're all worth viewing, but not in an unfiltered stream.
Rabble rabble rabble...