Well, EVH would not tell Randy Rhoads how he kept his guitar in tune. Rhoads GF reported he was upset EVH kept the secret from him (which I believe was the trem-stop EVH had installed in back of the floyd rose). I had read this from an online article but can't remember where.
I think if you happen to capture a little magic in your tone then you are less likely to share up front but eventually do.
EVH was notorious for keeping secrets and spreading false information about his playing and tone.