Signatures are trouble. 
They're either impossible to read or potential fakes, they add absolutely nothing to the beauty of the glass but often add arms and legs to the price.
At the risk of taking the thread on another detour, here's a tale for the amusement of Sue (and anyone else who reads it)…
A glass artist, whose signature I know well from older work I've collected in the secondary market, operates a gallery in which she sells her own works and those of other local artists. I indicated interest in a small piece by one of these others, and commented it's a pity it is not signed and dated, because his other works on show were marked that way. I was told that it could be arranged, if it was collected a few days later. I agreed, but was surprised when I saw it was engraved with his name in her handwriting.
My first thought was 'fraud', but I reconsidered. The attribution is correct and there was no attempt to imitate the form of his signature. It was never said that he would sign it, just that it would be signed. The piece in question is small and inconsequential - tourist ware really. As such, it might be considered generous to provide me with an enduring record of the maker and year. In addition, I have a conversation piece for those in the know.
I see all manner of (mostly hypothetical) questions here about values - both the ethical and pecuniary kinds - and of the definition of when something is "signed". But it would be a mistake to rekindle those controversies here.
Perhaps the whole tale says more about me than anything else. I'm not sure I quite agree with Sue on the role of signatures. Sometimes I suspect my collecting habits are less glass-works-of-art and more autographs-in-glass.
Trevor
[Mod: Quote from Sue's previous post added to the start of this post to make the context clear. This was done after I had made several "Mmmm" noises as a reaction to a possible need to shift this post into the Cafe! If there are further general comments about "prices and stuff" we may need to create a Cafe thread instead.]