What are the consequences of working in Thailand without a valid work permit and how does it affect visa status?

First time i read that the employee and the employer are being arrested:

Immigration police under the leadership of Pol Lt-Col Charoenpong Khantilo along with Department of Employment officials went to a school in the Don Yang sub-district of Pathiw, Chumphon in Thailand's south yesterday.

There they found a 50 year old Pakistani teaching without a work permit. She also did not have a passport.

She was charged with illegal working and illegal entry into Thailand.

The owner of the school was also arrested and charged with illegally hiring her, reported Naew Na.

Source: Naew Na.

But only one of them gets away with a fine, the other one goes in jail, visit court, goes back to Immigration Detention Center and after paying all the fines and one way air ticket she can leave the jail to go home and her name is on the blacklist between 0 and 99 years.

I read several times questions, how can i get a new Visa without the Work Permit? As you see, even when many people work without and tell no problem, it can go wrong and you do not want your photograph all over the internet.