Reviewers decline review invitations for various reasons. In most cases, they are either too busy with their work or they have already taken up other reviews. Since this is typically holiday season, many reviewers could be on leave. Another possible reason for declining a review could be if the reviewer is not very comfortable with the topic or if he/she has a potential conflict of interest. However, generally speaking, reviewers’ refusal to review does not tell anything about the quality of a manuscript. So, I don’t think the editor would have a negative impression about your paper just because three reviewers have declined the review invitation.
However, on rare occasions, the editor of a journal may return a manuscript to the author on the grounds of unavailability of suitable reviewers.
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