That brings up two points:
(1) Democrats understand their voting blocks and target them with simple slogans like "Bush lied" and "war on women". This is done for a reason.
(2) Democrat scandals are most often very complex and are not easily compressed into simple sound bites for the masses. Examples include the IRS scandal and the mess in Benghazi.
The Democrats know their base very well.
Actually, I contend that the scandals you mention are not inherently that complex. The complexity is added by their enablers in the media to confuse the issue.
If GW (or Romney) had been President when the IRS and Benghazi scandals broke, the MSM would have shown themselves superbly capable of simplifying them.