The first thing that popped up when I googled the phrase "Conflict of Interest" was an article that listed the basic things you should not do as a journalist, and the one that stood out to me the most was "Don't accept freebies or gifts from sources". Although this is the one that stood out to me the most, there are many other conflicts of interest.
In my opinion, I would feel really bad turning these gifts and freebies down, but it is a part of the job. In the article "Love Those Perks! / Critics Sound Off on the Ethics of Music Journalism", it states that "The ultimate challenge is to do good work based on fundamental respect for the community of artists and audiences in which you participate". Although, the person may feel that you are disrespectful for turning down their gift, just remember that your job and reputation is way more important. You are doing yourself a favor!