A specialist on the NYSE is not going to risk his or her high-dollar job by trying to cheat you out of a couple thousand shares of stock. They are subject to extreme scrutiny. But OTC versus listed is another topic. Essentially, I want to be sure that I can always buy or sell a few thousand shares within an eighth or quarter point, not dollars. Very soon, we won't have to be concerned about any fraction, since we are converting to decimals.
Percentages are percentages, and the results are the same from that perspective.
Your comments about the liquidity of lower-priced stocks, however, are accurate. Let me try to clarify this again. Professional traders don't invest money in each trade, and do not try for return on investment. Knowing that they will not have to pay any interest or hold the position very long, our traders don't think about how much money is being utilized. These traders want the stock to move a half point or so, or until the market tells them to close.