Cloud computing widely adopted by enterprises and individuals. Cloud computing provide several advantages but still there are many obstacles in cloud. Trust plays major role in commercial cloud environments. In the environment of multi cloud service provider, the assurances are not enough for the cloud users to select the trustworthy cloud service providers. Due to this problem, some cloud users have lack of trust in the services provided by the providers. This paper presents the importance of trust management in cloud environments. It also describes the feedback base trust issues when trust calculation done through feedback of cloud users. It is important to identify the feedback base attacks because less submission of fake feedbacks can also compromise the whole trustworthiness of service provider.