Like most guys I have a few close fishing friends that I "consider" telling but...I have found that they sometimes tell a close friend..who tells a friend...etc. and there goes the spot. It all depends on the nature of the spot...and if it's commercial season I only tell family....sometimes!
A funny story from back around 1970 shows how far some guys will go to get your spots. I had been hammering big fish at a Harbor UDL and a group of guys on vacation had seen me getting bait in the AM and bringing in fish later to the ramp. They asked the usual "where'd ya get em" question and as per my usual practice(my dad taught me how to lie at an early age

), I always told them a good spot to try...but not my spot. The 2nd day at the ramp they tell me they went where I told them and I was no where to be found. ..and they were mad! The 3rd day I arrived to get my bait and these guys and another boat were waiting for me; when I left with my bait both boats are hot on my tail. Well a 16 ft. alum. Starcraft w/a 55 Johnson can go pretty quick through some skinny water and I managed to lose them but I feared for my 19 yr. old hide when I went back to the ramp later. Luckily they weren't there...and I'm still here. If "don't ask..don't tell" is good enough for the military it's good enough for me!
