Here is the process for getting a tint violation in Maryland:
When you get pulled over, the officer will likely check the tint with a handheld meter, although this does not always happen. If the tint registers below the legal limit, or the officer believes the tint is too dark based on a visual estimation, he will write you a repair order. There is no fine for a repair order, however, you have 30 days to remove the tint before your registration is suspended at the MVA (DMV in other states). You can "appeal" the repair order by going to the State police, where they have more accurate testing equipment, however, it's not likely that your repair order will be reversed. Once the tint is removed, you need to have the car inspected at a certified state inspection station, who will sign and stamp the repair order, which you then send in to the state police. Again, if the repair order is not received within that 30 days, your vehicle registration is suspended.
In this scenario, cars registered out of state have nothing the police can hold over their head in regards to the suspension of the registration. Sure, they can issue you a repair order if they're so inclined, but if you do not comply, there isn't much they can do about it.
Source: having received two tint violations in the state.