You should strive for honesty because otherwise you will not get the most out of your employees. If you don't pay them as described here or forgo raises, they will respond in kind by working less, taking more time, and doing lower quality work aka slacking off. You think you'll be able to tell, but you won't because from the outside it won't be obvious. So you'll get what you pay for instead of what you could get if you paid honestly.