If I were to buy a signed guitar...I'll stop, I wouldn't buy a signed guitar.
That said, my DGT is signed by Grissom and Paul Smith, my SRV Strat is signed by Jimmie Vaughan, and Dick Dale signed my Dick Dale Strat (four times, once on the front) - you didn't tell Dick Dale where to sign.
Those signatures all mean something to me. I had them signed, I was there, I was in the moment...no one, but maybe my children, will care.
Unfortunately, a signed whatever is meaningless to me unless I can vouch for it.
Kind of a weird double standard.