SSPC Ratio. Just to be clear on what I mean by self-promotion, or if the term is right - shameless self-promotion (SSP). SSP is when you publish a post that only provides value for yourself (i.e. your blog, its ranks...etc) and not much for the reader. In my opinion, that includes return favors or exchanges like in the "Fave My Blog and I Fave Yours" post. However, SSP is not content promotion (i.e. pitching your post to an A-list blogger). In fact, Copyblogger notes that content promotion is a virtuous necessity.
Self-Assessment. So I did some calculations and my ratio turns out to be 0.039 (from 8/204) which means about 4% of my posts are for self-promotion. Yes, that includes my Keep Your Readers Thinking widget but I guess my SSPC ratio is OK. I noticed that choosing the posts that DO provide value from those that DON'T is a little bit tricky because some posts did have original content along with a "vote for me plz" somewhere in it. So I counted those as half (1/2) shameless self-promotion posts.
Comparison. Now the percentage I found for my blog doesn't really mean much on its own so I wanted to compare it with other bloggers. Immediately a few bloggers came to my mind who has been doing a lot of self-promotion lately. However, thinking it over, I didn't want to drop names and numbers here because some people might not agree so on and so forth. Feel free to drop yours off, but if you are going to, please be honest. I'm not interested to see "Hehee I has 0% SSPC" comments!
My advice: If you are going to do self-promotion, you must have content to back it up!
Now the big question is: What should be the standards, intervals or critical values a legitimate blogger should seek in their own SSPC ratio?