HI guys
Typically on the guitar we see E# as F, and the reasons why are related back to the notion of equal-tempered tuning and the efforts of a Mr Bach in producing a series of works entitled 'The Well Tempered Clavier'. I won't bore you with the details now, but when we think of E# and F we are thinking of enharmonic notes.
When we play on other instruments, or play
slide guitar, the compensation we need to allow for tuning is more noticeable. On the piano we are fixed with the pitch we can play, but on other instruments we can manipulate the note to bring it closer to being 'in tune'.
The mathematical proposition of 12 tones means that tuning is compromised to allow us to modulate bewteen keys (see Bach as I mentioned earlier).
I play sax as well as guitar, and tuning is compensated by the embouchre (how the mouthpiece is held by the mouth) constantly to work with the inconsistencies of the tuning system we use.