Problem
I disabled trackbacks in the general WordPress settings, used the Simple Trackback Disabler plugin (because i’m too lazy to do it in mysql) and I still got trackbacks.
Solution
The Simple Trackback Disabler apparently doesn’t disable trackbacks for attachments as of this writing. Next time, don’t be lazy, just do the sql query:
update wp_posts set ping_status = 'closed' WHERE `ping_status` = 'open'