DISADVANTAGES:
If the son has current creditors they might seize his interest in the house. Or his future creditors (say he is in an accident and has inadequate insurance) may do so.
The value conveyed would be a gift to the child, and a Gift Tax return may have to be filed. (No big deal.)
Could impact householder's or other exemptions under local property tax.
Son could totally screw his parents and seek to divide the property, force a sale, etc.
If son dies first (and it happens), who gets HIS share? Might such person(s) screw his parents?
Might it affect the title insurance or any mortgage?
ADVANTAGES:
When the last parent dies, if the property was held in Joint Tenancy with Right of Survivorship, it would pass by operation of law to the son (if he is alive) and there would not be any need for probate with respect to the HOUSE, although there still likely would have to be probate on the rest of the estate.
CONCLUSION:
The parents normally should keep ownership in their names, and get a Will prepared and properly executed. If there are questions as to posible need for Medicaid for a Nursing Home, or the estate is large, a lawyer should be consulted NOW. A Living Trust is likely a better way to handle it.