I think it is called campaigning. Both sides will be bringing up the weaknesses of the other candidate. Like any advertisement there will be embellishment and selective historical reporting.
Do you think Obama can win if he goes around saying that McCain is really a pretty good fiscal moderate.
Or McCain winning saying that Obama is bringing new ideas that just might work.
Of course not. That is not how our system of adversarial political parties works.
Obama has to treat McCain like the incumbent (old ideas, continuing bad policy) otherwise he can't get his message of change across. It really does not matter whether McCain supported or did not support the policies of the past administration, Obama will say that he does.
McCain has to treat Obama as radical with untried and risky policy. It does not matter whether Obama is or is not a radical or whether his policies are risky or not, McCain will say that he does.
We call this crap: politics
And we really should not pay all that much attention to it. We have two lying piece of crap politicians willing to say anything to get elected - That's the American way.
It is a fight between two personalities and it will get personal.
In the end, people will vote for whom ever they feel will be better for the job. By this time, I doubt that too many citizens are truly undecided (maybe 5%?)
So let the salesmen say their piece, it is what they get paid for.