So my strategy is - my wife won't notice if I just replace one of the older ones on the guitar stands with a new one and put the older one in a case out of sight for a while. Then it's a month or so later and when asked - " hey did you buy a another new guitar?" I just reply - "nah - i've had that one a while" 
I recall reading a couple of lines off some guitar T-shirts that go.....
" Go On - Buy it - you can always get another wife!"
or
Dear God
Now I lay me down to sleep , I pray the Lord my soul to keep
If I should die before I wake, please don't let my wife sell the guitars for what I told her I paid for them! 
But seriously - my wife is very understanding and as long its bought with money that I stashed from odd jobs I've done or coaching pay - she really doesn't care - besides that - the value of her shoes collection is more than my guitars I fancy. 
My biggest wish is that my guitar playing ability was equal to the quality of my guitars
and heaven knows if it was - I too would be a true guitaraholic as well.
If guitar stores made a rule that you have demonstrate excellent ability before they could sell it to you I would be SOL ! 
Cheers and good health to everyone
Jim