In the lessons, one of the first thing suggested is to tune the guitar. I have 4 different electric tuners and 4 different settings. Have a Snark clip-on tuner, Rocksmith tuner, built in tuner for amp (Fender Musting I V2), & phone application tuner.
All of these seem to give slightly different tunes. I have been just using the Rocksmith tuner because that is forced during that play time. Is there any way to test the accuracy of any of these tuners? They seem non-adjustable.
Perhaps you could test them against a piano or even a tuning fork ( concert 'A' 440 Hz )
On the internet you can search for accurate tuning tones as well.
I tested my Spider 6 amp tuning feature against an internet tone and it came out quite accurate. My clipon digital tuner, on the other hand, didn't fair so well. I have a Korg metronome / tuner that gives out various tones and that was quite accurate as well.
Joe.
To be honest, as long as the tuning is close enough to what the note frequency is, then you should be okay. The idea is to get your guitar sounding as close as possible to the correct tuning. But with the way sound works, it's darn near impossible to have the perfect tuning frequency!
Thank you for the feedback. I figured the response was going to be get it close & don't worry about it. Getting the varying results with very narrow tolerances of "correct" with each device was bothering me.
I will try to find some reference tones and see how that matches with the different tuning methods and go from there.
Maybe not entirely the same issue... but I have had problems in the past with tuning the guitar, playing it once and it being slightly out.
I resolved it by making sure I had enough windings on the peg, not over stretching the new strings (which left me with overly stretched sections of string believe it or not) and Big Bends Nut Sauce) to lubricate the nut.
Made a massive difference!
I use a Snark clip-on and have no problems now.
My duo spent half our time tuning and the other half playing out of tune. 
