Make a org-mode table.  In one of the cells of the table, have some text that is +struck out+.  Note that the struck-out text is default text color (black, for me), and not org-table text color (blue, for me).  It's even worse if you're running org-variable-pitch-mode, because the text also won't be set in a fixed-pitch face, and so will screw up the alignment of table text.  I found out why.

When org-do-emphasis-faces constructs the new face that it applies to the text, it passes the lookup value from the org-emphasis-alist to font-lock-prepend-text-property, which makes a list, composing it with the existing face.  This would fail for strike-though mode in a table, since the org-emphasis-alist lookup would return (:strike-through t), resulting in a face of (:strike-through t org-table), which is an invalid face, and then emacs has no choice but to render it unfaced.

Attaching a patch for the issue.  Rather than try to figure out how to make org-do-emphasis-faces somehow smart enough to deal with this situation (I'm not sure it's possible, in general), I took the easy way out and defined an org-strike-through face which can be used in org-empasis-alist.

Humbly submitted for your approval...

~mark