In politics, if something sounds too good to be true, it usually is. That is a lesson both for Gov. Bobby Jindal, and for those who push him to expand Medicaid insurance for people in need in Louisiana.

The Legislative Fiscal Office suggested that taking the federal aid that would expand health care would be a financial boon for the state. Too good to be true? At least in the long run, maybe seven to 10 years out from the initial federal grants. Supporters of the expansion should not make too much of the financial analysis.

The Fiscal Office’s analysis is surely correct that the state will be able to save money in some ways, even as it expands the eligibility of Medicaid to include people with incomes up to 138 percent of the poverty line.

Part of the savings is in prisoner care, now purely state-funded but paid for in future with Medicaid money matched by the U.S. government at a very favorable rate. Other such swaps and adjustments, aided by the 100 percent federal reimbursement for new enrollees in the first three years, would yield significant savings to the state.

However, we caution about the “too good to be true” rule: If the working poor have been avoiding medical care for some ailments because of cost, they’ll probably go to a doctor — and that utilization would increase costs. Common sense also suggests that people scrimping by with a job at a fast-food restaurant, for example, might well have put off medical care until the pain, and perhaps costs for more complex treatment, grew considerably.

We suspect that the Jindal administration is alarmist about potential costs, but neither should the advantages be oversold. Part of the legislative drive to expand Medicaid would make it a subsidy for private insurance to expand options for recipients. That may or may not reduce costs, either, but in principle it sounds like a good idea.

Jindal and the Pelican Institute for Public Policy are pushing another party line that violates the too-good-to-be-true test: Medicaid actually harms the health of recipients.

This is based on a misreading of an Oregon study, based on two years’ experience comparing health outcomes for some patients in Medicaid and some uninsured, with the Medicaid group actually slightly worse off.

Health outcomes, especially if one hasn’t led a particularly healthy lifestyle for years, are unlikely to be turned around in two years. The anti-Medicaid talking point taken from the study has been often debunked by national analysts, including columnist Robert Samuelson in these pages.

Embracing that false notion says something about the critics of the Medicaid expansion: a lack of empathy for those making low wages.

The most-dedicated saver in a janitorial job is not going to be able to afford health insurance that is worth any meaningful amount of coverage. What Medicaid provides is hardly gold-plated health care, but it is protection against utter destitution if a worker gets sick.

That’s worth something, even if it’s only peace of mind. Critics ought to realize that the “Medicaid hurts the poor” argument defies common sense.

The too-good-to-be-true rule remains in force.