Question: I playing guitar since a couple of years (but not regularly) and I always wondered if guitarist from known bands always play their songs/solos perfectly?
Especially when the songs are fast paced, is it easier to make mistakes that no one will notice? When I play solos I am never really satisfied with my performance since it doesn't sound exactly the same like in the song.

I know there is no exact answer but I would like to know what you think so I can silence my conscience :)

Answer: 
I would expect that the musicians in top bands play extremely consistently, due to sheer repetition and the fact that it's their career.

However, your question touches on a trickier idea: What exactly is a "mistake"? If the exact notes and rhythms are prescribed, then any deviation from that clearly constitutes a mistake. But how precise does the timing/tempo need to be for the rhythm to be considered correct? What if it's technically correct, but a bit off stylistically or emotionally? What if something is "supposed" to ring out, but the fretting was a bit off and a note got partially dampened?

And what if the music is improvised?

From the listener's perspective: would you rather listen to a solo that was beautiful but had a wrong note, or one that was technically perfect but soulless? Anecdotally, my favorite rendition of a Debussy piano piece has a blatant key signature mistake in it\*, but it's still my favorite due to every other aspect of the performance. My old piano teacher tells a story of performing a section of a Bartok piece in the wrong *clef*, and people still enjoyed it.

The whole idea of perfection and mistakes is not very well defined, and in performance art it must be that way. Ultimately, the question is not whether or not a performance was "perfect", but whether or not it was enjoyable and conveyed whatever it was supposed to.

---

\* For the curious: [Van Cliburn's recording of Jardins sous la pluie](https://www.youtube.com/watch?v=m8rXQCewQjA). The section in C# in the middle, he misses B# in the melody each time.
I am not a guitarist myself, but I know a really great one and he assures me that he has never played all the way through a song without making a mistake, nor has he ever played a piece through exactly the same way twice. He's always tweaking things here and there. If you're comparing yourself to recordings, you have to realize they do multiple takes and combine the best takes. Even then, nobody is hardly ever perfect.

And please do silence your conscience! This is not what it's there for!