There is something distinctly unsettling about political parties admitting to deceiving voters on the doorsteps and shrugging it off by saying "everyone was at it".

Asking the electorate to trust politicians to run the country, when parties can't be trusted to tell the truth to householders, illustrates why leaders frequently suffer from a credibility deficit.

To recap: Fianna Fáil, Sinn Féin, the Greens and Fine Gael have owned up to using party supporters to do private polling instead of hiring market research companies.

That much is fine. But the misrepresentation is a problem.

Why do the polling under a false flag? If a political activist conducting research admits to a voter they are with a party, it immediately influences the result of the survey.

"If you say who you are it skews it straight away," one party official said. People can become more guarded about their voting intentions in those circumstances.

To circumvent that, party members or students lied and said that they were working with fictitious polling companies. Some were issued with false business cards.

Hiring a professional firm to do a poll in a constituency can cost between €10,000 and €20,000.

This week, Sinn Féin's Housing Spokesman Eoin Ó Broin said when his party did not have those resources it used its own supporters instead of market research firms.

The Data Protection Commissioner will be looking at the issue as part of a wider trawl of political parties.

If the parties did not retain personal information, such as names and addresses, it appears unlikely they would fall foul of data protection issues.

That probably means there won't be sanctions against them.

But the issue serves to illustrate that many of the problems surfacing about how parties manage their affairs, such as Sinn Féin's handling of records kept on voters, have arisen because of a lack of regulation.

At present the Fianna Fáil, Fine Gael and Green coalition is legislating for an Electoral Commission.

The body will have investigatory and enforcement powers, according to the Department of Housing and Local Government.

The aim of the commission is to end party funding from outside the State, oblige leaders to sign an adherence declaration, regulate the property portfolios of parties, and regulate the subsidiaries of parties.

How private polling is handled isn't mentioned. But clearly it is something which could, and should, be included.

Polling is expensive. Professional market research companies such as RedC, Behaviour & Attitudes and Ipsos MRBI are members of the Association of Irish Market Research Organisations, which sets rules for the industry.

For a snapshot of voter intentions in a local constituency, a poll needs more than 500 participants to complete a sample ballot paper, and be representative on the basis of age, location and a gender. It would normally have a margin of error of plus or minus 4.5%.

Polling companies have put enormous resources into ensuring they comply with the requirements of General Data Protection Regulation, or GDPR.

When they hold information such as a person's name and address they have to be careful about where the data is stored and for how long it is retained.

If any political party has posed as a fictitious polling company and held personal information on individuals, it would give rise to a host of problems.

Under GDPR, participants in polls have a right to retrieve their information or ask to have it destroyed.

Obviously, that would be impossible if they were given the name of a fictitious polling company.

Independent TDs frequently used money from allowances paid by the Oireachtas to commission polls.

One experienced political campaigner in a large party told me the private polls conducted by supporters fell so far below the standards of professional companies that they were hopelessly inaccurate.

"Even with a professional poll people have so little awareness of candidates until an election is called that you don't get an accurate view. Frequently when presented with a sample ballot paper people just tick the names they know."

Green Party Deputy Leader Catherine Martin told RTÉ's News at One this week that party supporters posing as pollsters "should never have happened - it has no place in politics".

All parties now say the practice has been discontinued.

But the fact that any of them thought it was acceptable in the first instance is remarkable.