it's considered the death of any company in general. the the last place a company wants to be due to the public perception of the company's ethical practice and behavior. But it's not always perception...more so then not it is fact. Grey market is not where one wants there investment to end up.

reasons: public perception, unethical business practice, very low liquidity of the stock, no market makers, no market essentially. no sec to regulate the company. not regulations for the company to follow and they are not required by sec to file anything EVER!!! LOL
No market makes the stock difficult to sell; brokers don't generally deal with this stocks and often will only trade them with special instruction which usually comes with a premium to trade or liquidate. They also want to make money.

Basically looks REALLY BAD! LOL.

however, there are plenty of solid company's who have chosen not to uplist to higher tier to save money and still operate a legitimate prosperous business.