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: 
Other answers are great, but I'll add my experience. When playing live with a band, you have a lot going on at the same time. So mistakes may be masked by the rest of the band.

Most importantly though, is that you roll with it. Not just from the perspective that mistakes can still work, but that if you let it get to you, you are more likely to make more mistakes. Instead, just keep going, the audience can't rewind to hear your mistake again. If you can finish strong, that's what they will remember.

I love this [video](https://www.youtube.com/watch?v=wn1pk8Lpelc), and it's the perfect example of rolling with it. SRV breaks a string and his tech replaces the guitar in basically a four measure break that was there anyway.
“Never lose the groove in order to find a note.” 
― Victor L. Wooten, The Music Lesson: A Spiritual Search for Growth Through Music

This acknowledges that musicians do play "wrong" notes, but what's more important is the flow of the piece. As for "wrong," it depends on how formalized the piece is. Some classical music has a fairly rigid structure, and the performer is usually expected to play the music as written (note-wise, not speaking of interpretation here). Celtic tunes on the other hand have "settings" (i.e. ways of playing) that may vary, so a musician who plays a "wrong" note may claim it as a new setting; but of course playing a C# in the key of F may raise eyebrows...

I like the comment above about being one fret from the "correct" note, and that's what slides are for.