The main reason for refusal is the consular officer's suspicion that you plan to stay and live or work in the United States. That is, having arrived in America as a guest, you will start knocking on the doors of the Immigration and Naturalization Service (INS) in hopes of changing your status, or try to find a job, or worse – settle in the country as an illegal alien. Therefore, the main task of a visitor visa applicant is to prove the absence of immigrant intent.
It must be said that this is no easy task. According to US immigration law, there is a so-called 'presumption of guilt' regarding foreigners: the law requires consular officers to see a potential immigrant in everyone. Therefore, Americans take documents intended to attest to your unwavering desire to return home seriously, with an offensive but quite understandable distrust.
In dealing with embassy officials, it is especially hard for those who have previously expressed a desire to immigrate to the United States. If your immigration application is currently pending at the relevant US agencies, you can rest assured – you will definitely not get a visitor visa.
If you have previously been denied an immigrant visa, you will have to work hard to prove that your life has changed radically and that your immigrant intentions have completely disappeared. For example, you have found a great high-paying job, your own business is doing well, or relatives have appeared who left you a substantial inheritance.
Special mention should be made of participants in the annual green card lottery. According to US Embassy officials, neither the fact of applying for the lottery nor even winning it is irrefutable proof of a person's immigrant intent. Therefore, lottery participants – current or past – are no different from ordinary visitor visa applicants.
It is a different matter if, having won the green card lottery, you have already sent documents to the INS and thereby declared your immigrant intent. Then sit and wait for the INS to process your case. And until that moment, forget about America.
And lastly. The biggest mistake you can make is to try to deceive the embassy. For example, your immigration case is pending at the INS, and when filling out the visitor visa application, you write that you are not even thinking about immigration. Or: you have already applied for an immigrant visa ten times, been refused as many times, but still write that you have no immigrant intent. If you are caught in such a lie, you will not only fail this time, but will never get into the United States at all.