He is.
Do you forget:
-"the Gingrich Who Stole Christmas"
-three marriages and MESSY divorces
-his overall bad reputation in the media
-the ethics charges (which IIRC were NOTHING compared to many pols ethics issues)
I'd like to think so, but here's my analysis:
Bush won because he got conservative turnout and enough of the independent vote.
Gingrich would get almost NONE of the Indy vote unless people have forgotten all the (mostly trumped-up) "corruption" he was accused of by the media in the 90s. He'd get the fiscal wing of the GOP for sure, and depending on his immigration stance and WOT views, he could probably get those too, but a lot of evangelicals would sit out. And he would get virtually NO Dem crossovers, he's as hated by the Dems as Hillary is by us.