Companies so tiny (in terms of market cap, share price, and liquidity) that the NASDAQ, American Exchange (AMX), and NYSE wouldn't touch them with a ten foot pole.
Playing black jack in Vegas has better odds than trading pennies/pinks/over the counter stocks. Massive spam campaigns tout them as "Going to the moon!" These campaigns do drive the price up short term, but people who buy a day late typically lose money, and touts are usually long gone by then.