Well, Alan, I neglected to mention that at least 1/3 of the times when I've showed up for a gig sans my guitar were BECAUSE I had left said guitar at the earlier gig. LOL
Thus, SNAFUs compound like interest does (or at least used to).

(Then there are the times when the room really called for an amp and mic and I had it all with me -- EXCEPT for a) a 2-prong to 3-prong electrical plug adapter, b) an XLR to 1/4" condenser/adaptor, a mic stand, c) some similar minor but essential link in the 'chain', or d) more than one of the above. (I seem to recall something about a battle being lost for want of a horseshoe nail or the like.)   But then, that's a subject for a whole nuther thread (e.g., about what can scuttle a whole gig.