I think the whole idea behind internal polling is this:
TRUE internal polling is the kind that campaigns don't release to the public. This kind of polling is where the campaigns are interested in knowing the most accurate information possible about their standing in the various states and with different kinds of voters so they can most effectively make changes in where they campaign, how they campaign, which voters to target etc. There is no benefit to making artificially good news here.
If the campaign is down around 2% in Ohio, it's important to know that because then maybe more canvassing and calling is needed there, and if the polling shows that the candidate is weakest among union workers, or suburban housewives or whatever, perhaps a targeted ad campaign towards that audience is in order. Or, if the campaign is down 5% in Ohio despite massive ad campaigns and canvassing, perhaps Ohio is hopeless and the electoral votes are better made up in other states (but you still put on a happy face/happytalk for Ohio lest you be seen as conceding the race).
Getting inaccurate information in private internals serves no purpose except to make people feel better until the race comes crashing down around them.
The purpose of LEAKING internals, which could be either real numbers cherrypicked from a series of samples, or totally made up, is simply to try to combat a media narrative that your team is cooked, lest your voters get discouraged by a flood of bad news and turn out less than polls even show and cause a downticket disaster, or cause you to lose close states that you might otherwise win by a hair. Obama's campaign was criticized earlier (perhaps during the post Debate #1 Dark Times) for leaking internals, can't remember whether they were national or for what state, and rightly so I think.
It's almost certainly a sign of weakness. Obama's people have no need to leak internals right now because the vast majority of public polling, that is not affiliated with their campaign, is showing a won race for them. That data, barring heavy Unskewing, is showing a lost race for Romney and that narrative in and of itself could cost him a close race in CO, FL, NH or NC and cause downticket harm, hence the perceived need to shoot some holes in the "Roms going down hard" narrative.
And, unlike pollsters, campaigns don't have accountability for accuracy in these leaked internals. If Romney's leaked internals are grossly off the mark, the worst thing that happens is that he lost the election anyway. Even the professional pollster that does the internals for him will be forgiven, because everyone will understand the need to float bullshit numbers for media purposes in certain situations. On the other hand if Rasmussen, PPP, or Gallup call every race in the wrong direction and off by 8 points then their reputation as a pollster is shot and they are no longer useful for their primary business providing polls for media coverage.