Much of the opprobrium was richly deserved. There may not have been grounds for prosecution. But there was a problem of perception surrounding his contacts with internet millionaire Kim Dotcom and casino operators SkyCity.
Banks' pretence otherwise only made that more of a problem. His deaf-and-dumb routine on TV One's Q&A was in the realm of the truly bizarre - as was his now immortal statement about "not having come up the river in a cabbage boat".
But even the most cold-hearted politician would have winced at the fate he suffered in the House one evening. Normally, a victim of ridicule can leave if he or she cannot stomach it. As the responsible minister for a bill which had reached its committee stages, Banks was required to stay in the House. He was trapped. Labour MPs rounded on him mercilessly.
In obvious reference to the incident, Banks told the Weekend Herald that the debating chamber was a "very lonely place for the lone traveller".
In such circumstances, a minister could expect party colleagues to rally and offer some protection or distraction. But Banks had no one.
No doubt the thought that he might still be alone for another three years after the next election was another ingredient fuelling the invective directed at the Electoral Commission. He could have hardly been surprised that the commission advocated the scrapping of the so-called "coat-tailing" provision as part of its Government-ordered review of MMP. This rule means parties which win an electorate seat are automatically exempted from having to reach the 5 per cent threshold for the party vote and can bring extra MPs into Parliament in proportion to their lower party vote.
Act has benefited mightily from what has long been considered an anomaly in the electoral system. Rodney Hide's victory in Epsom in 2005 left National with little option but to do a deal in the seat with Act in 2008 or watch the latter party's votes go to waste. Act delivered in 2008 with four such extra MPs. Last year Act failed to deliver. Now what would otherwise be a rock-solid National seat is all that stands between Act and oblivion outside Parliament.
Removal of the coat-tailing provision would effectively end Act's utility for National. But National - as the governing party - has to decide whether or not to write the legislation that pulls the trigger.
Staring down the same abyss, United Future's Peter Dunne has been guarded about what National should do. Not so Banks. He has sought to discredit the commission as being incompetent, while accusing the quasi-independent body of succumbing to submissions from Labour and the Greens who sought to gerrymander the system in their favour.
Banks then further upped the ante by predicting National will not have the political will to "gas" its two most reliable and effective partners.
He is right in one respect. It would send a dreadful message about the long-term value of major-minor party relationships in coalition arrangements. On the other hand, National will look both self-serving and disrespectful of the commission if it does not pick up the recommendations.
One option might be to delay the Government's response to the commission's findings so that they cannot be implemented in time for the 2014 election. An only slightly more credible alternative would be to shift the implementation date for any changes to the electoral system beyond the next election on the grounds parties need more time to adjust. Both scenarios would leave National open to the criticism that it is gerrymandering by not acting speedily on the recommendations of the commission when it tasked that very body with remedying those components of the system which the public dislikes.
Another possible way of easing National's dilemma would be to ignore the commission's call for the "overhang" to be abolished.
Without going into the mathematics, sticking with the status quo could see Banks' and Dunne's two votes being retained for the centre-right without National losing a seat - which is what would have happened if the current Parliament had been capped at 120.
The benefit might be marginal to National, but it is likely to be operating on even thinner margins at the 2014 election than last time when it comes to retaining power. The trouble is that option does little to help either Act or United Future.
The decision might ultimately come down to National assessing whether there is any point in providing safe harbour for Act or United Future any longer and stand candidates in their seats with the intention of winning them.
To some degree, Act's and United Future's fate is in their own hands.
If they were to start polling around 2 to 3 per cent, National would be much more reluctant to ditch the one-seat threshold. Both parties, however, have been struggling to even register in the polls this year.
Banks sees his job as two-fold: ensuring Epsom is Fortress Act while refocusing the party's message to appeal to what Act sees as an untapped market of hundreds and thousands of owners of small to medium businesses.
This audience is seen as sympathetic to the Act product - highlighted by what the party sees as its "breakthrough" policy of charter schools. The question is whether Banks as Act's messenger - having suffered more knockdowns in his political career than Lazarus - can rise once more.
Many will see the Dotcom saga as just one more colourful episode in a very colourful public life. But many will see it as Banks' final and not easily forgotten blunder.
