People have already made up their minds about allegations contained in an unauthorised biography of him, David Cameron has claimed.
The Prime Minister refused to address the detail of claims which have already emerged from Call Me Dave, written by former Tory donor Lord Ashcroft and journalist Isabel Oakeshott.
The biography, which was serialised in a newspaper, is due for publication in full on the Monday of this week's Conservative Party conference in Manchester.
One of the allegations already in the public domain, which was dismissed as nonsense by sources close to the premier, was that Mr Cameron participated in a stunt while at Oxford University involving a dead pig and "a private part of his anatomy".
Mr Cameron told BBC One's The Andrew Marr Show: "I think everyone can see why this book was written. The author wrote an article himself explaining why he was doing this.
"I think everyone can see through it, so frankly I am not going to dignify it with individual responses. I think people have had a look and they have made their mind up."
Mr Cameron said it would be "completely wrong" for anyone to get a Government job on the basis of being a donor.
Lord Ashcroft - who gave the Conservatives £8 million while the party was in opposition and led a drive to win marginal seats - has said he decided to write the book when Mr Cameron declined to reward him with a sufficiently senior job in government when he came to power in 2010.
Mr Cameron told Marr: "I appoint people on merit, on their ability to do the job, and not on anything else."
The Prime Minister also told the programme that his party had paid off its debts, including money owed to Lord Ashcroft.
He said: "When I became leader of the Conservative Party, the party had debts of about £28 million - money we owed, including to Michael Ashcroft. I have repaid that, I raised money from elsewhere and repaid that debt because I didn't want to be in people's debt.
"The Conservative Party today has virtually no debts at all. We have raised money, we have broadened our fundraising base, we have paid off all these loans, paid off all these debts, because the party I run, I don't want to be in anybody's debt."