American immigration laws are kind of silly in that they want to control your intentions, not only your deeds, so if you come to the USA on a tourist visa with the intention of looking for work and later staying then you are technically violating the law. Immigration people will often question people about their intentions and try to trick them into incriminating themselves. If you say you have no intention of seeking for work and ou later find work the issue has to be handled very carefully because if they determine your intention was to look for work in the first place they will have grounds to deport you.
A Mexican friend of mine married an American citizen and recently went to the interview to get her Green Card. She was coached by her lawyer very clearly that she should not say she came to the USA with the intention of getting married and to say that she had never even thought of getting married until she arrived in the USA as a tourist and later the guy popped the question and that was the first time she had even thought of marriage. Because if they determined she had entered the country with the intention of getting married then they could kick her out on the grounds that she her misrepresented her intentions.
In other words, you can come on a tourist visa with no intention of looking for work and then find work by chance but you cannot come on a tourist visa with the intention of looking for work and if they determine you did this then they will deny you a visa.
That is one reason immigration officials are routinely rude and confrontational: they are trying to make people nervous and hope they will give away this kind of information.