HERE's the post of mine you mention, criticizing the equivalency defense of "well, Republicans do it too".

What I criticize is that Democrats use it to hide that their guy is wrong.

In the same situation, Republicans admit that the offending conservative is a scumbag, as they point out Democrats who did the same thing. That's acknowledgement as well as equivalency.

Whereas Democrats tend to use the equivalency argument to hide that their guy did anything wrong.
And when a Dem is caught (Clinton: perjury, Monica Lewinsky, for example) it's characterized as "picking on" Clinton, and Hilary gets her talking points out that it's part of a "vast right-wing conspiracy".
So even when a Democrat does something wrong, they're absolved of guilt and the Republicans are blamed.