Sweetglass, I've taken out those images as they belonged to sellers on ebay, not to yourself. I've provided links to the two auctions you meant instead.
Firstly, many of us here buy glass on ebay and then re-sell it. There's nothing wrong with that at all, so it's no good complaining that a seller bought something as 'nothing special' and sold it to you at a greater price.

Murano glass is not without imperfections. If a piece of glass is handmade, then chances are it's going to have (as TxSilver said above) bubbles, bits of frit or ash or lumps on it. So...as long as the piece conforms with what the seller said, ie it's got a small scratch on it, then you can't complain about that either.
Howeevverrr....the photos seem to be vastly misleading for colour IF the original seller (who sold it as 'an ashtray') are correct. The colour variation is far greater than differences in monitor settings and appear to be misleading.
Don't muddy your claim against the seller by citing 'it's not perfect' or 'you bought it as an ashtray', that's not the point. You can simply say that you feel the photographs were misleading colourwise and hope that should be enough.