Most logo designers fail to grab the very essence of logo designing, which continues to be the need for originality. Yes, research does have its space in this field and there is a good deal that you acquire from your experience of knowing and understanding the stalwarts in the industry but nothing is lamer than spinning existing logos to call them your own.
While inspiration could be a driving force to make you better at your work, imitation is clearly not a wise idea. A lot of designers tend to modify existing designs by altering the font, trying new font colors while the original logo stares right back at you. This ends up adding zero credit to the brand value and also renders your efforts meaningless.
The best way to approach inspirational work is to study the idea behind the creation and to learn new ways of adopting the techniques involved.