Originally Posted by fried

An unintended consequence to this is that after 30 days, you are liable for income tax to that state and/or city. In most cases the hotels do not report you to the tax authorities, but I've heard of cases where the local cops do a parking lot check every 30 days or so and trace down from the license plates who has been there long enough to be liable for income tax.

Also, sometimes the law is less than 30 days. A story I read in the Boston Globe talked about how the local law was structured so they could charge income tax from out of town sports athletes like MLB players for the few days they stayed at hotels playing the local team. Since these guys make millions, charging them income tax for 3 to 4 days of the year generates a lot of income.