Nerofizz - Writers often fear they will be seen as frauds, because they feel their readers give them too much credit. If people call you brilliant, or hilarious, you become terrified that sooner or later readers will find out that you're in possession of no more than the average slightly-above-average intellect, and that you're really not that funny after all. Readers (especially avid fans) often confound the problem by noticing references you did not intend to make, connecting dots you never planned to have connected, and overall elevating your work to a higher level than you feel it warrants, given the conscious effort and intentions it took you to produce it. (Of course, for every fan that thinks you're the second coming, there will be three who think you're the literary equivalent of the antichrist.) Even with my (up-to-this-point) limited exposure to publication I've experienced readers giving me more credit than I'm due.
Also, there's the fear that whatever good writing you've produced up to now has been some kind of a fluke, and that you'll wake up tomorrow and from that point on only ever be able to produce what anyone in their right mind would rightfully regard as rubbish. After all, we don't know the answer to "Where do the words come from?" or at least, we don't know a satisfying answer. And so this makes us superstitious.
Sometimes.
I was in a pit of self-doubt once, and a friend with very good professional judgment complimented me on something I'd done well.
"You're just saying that because you're biased," I retorted.
He looked at me calmly, clearly unwilling to take any crap from me. "Yes, I am biased," he replied. "I'm also right."
It worked.
Of course I'm not saying that the opinions of those close to you can't be right. I'm just saying you can't trust them.
For example, my mom and I have very similar reading tastes. She reads a lot of books that I give her. When she told me how much she liked a recent novel of mine, I believed her. I think she's right. I think the novel is good, and her liking it is justified on grounds other than the fact that I came out of her womb.
My mom also told me that she thinks my novel is just as good as John Green's
The Fault In Our Stars.
While she is of course entitled to her opinion, I take that statement with a grain of salt. Would she really say that if I weren't her son? Impossible to say.