My dad has dealt with this for a while now.

My dad works full time (and lives M-F) in Nevada. My family lives in Utah, but all of the kids are married except for the youngest. Utah law says that if you have a spouse or public-school aged child who spends more than 180 days in the state of Utah, you are considered a Utah resident, no matter where you live. My dad has had to pay income tax in Utah (despite the fact that he literally doesn't live in the state) for the past few years. If Nevada had income tax, he would have been having to pay both taxes.

After my brother left on his mission, my mom lived between Utah (to be near the kids) and Nevada (when my dad wasn't travelling for work). When tax season came around the State of Utah said that absent affirmative proof (flight records, etc) that neither my mom or dad were in the state for more that 180 days, the State would assume that they were in the State for more than 180 days, and would tax them as residents. This year they've literally got a file full of every flight ticket and a spreadsheet created to prove when they were and weren't in the state. Fingers crossed, things work out.

I think the situation is a joke. Seems like the State of Utah is playing fast and loose with the burden of proof requirements under the tax code, but I don't know enough about tax law to know anything.