Often, the comment/trackback/ping count is one higher than what actually appears either under the post or on the dashboard. I have at least one case confirmed where a trackback post on Blogspot may have been counted, but did not appear under the post.
I see many queries here about comment counts being too low, or zero, but I seem to be the only one experiencing this one-too-high problem, or possibly missing trackbacks altogether.
Annoyingly, many scrapper trackbacks do appear and are counted; it only seems to be honest trackbacks that get counted but not displayed.
This problem has persisted across many updates of WordPress and with and without a variety of plugins.