There are many reasons for US visit visa refusal in B2 category.
The information mentioned in the forms and proofs submitted in form of supporting documents have a very close relationship.if there are lack of documentation then the visa officer may assume that the information mentioned in the forms is misleading so he can reject your visa application for US b2 visa.
Visa interview problems
USA is a country which takes interview of each and every applicant. The misunderstanding of visa officer question , bad attitude, inappropriate dressing, wrong answers to the questions asked by the US visa officer may result in refusal of visa application.The body language including the eye contact is another visa interview problem as some times the visa officer assume that the applicant is not answering the question truthfully.
Lake of business and employment history of work status
US visa is awarded to person who have a good working status in their homeland country and lack of business and employment history may result in refusal of the US visa.If a person is not working in his country or his previous employment history as employed and self-employed person is not satisfactory then The visa officer might assume that the person is visiting USA to seek employment opportunities and he may not return to home land country.
Lack of family ties in homeland country and abroad may result in refusal of us visa application.if a person has no close relation with his sponsor in USA then his visa might be refused.
USA trip is expensive task. The visa officer judge the affordability and financial stability of US visa applicant. Lack of financial background may result in refusal of visa application.
Long Stay on visit visa
In all visit visa applications the US immigration authorities assume that the visitor will stay for short period of time like 1 week to maximum to three month for family visitors. If a us traveller has a previous travel history of USA or even other countries then the time period of his stay is also considered. If visa officer finds unusual long stay periods then he might assume that the applicant was doing some job and his visa might be refused.