As I mentioned before, to the untrained eye, all gondolas may look the same. Closer scrutiny however, reveals charachteristics unique to each boat.
The third gondola I observed had a few unusual details:
The green canvas bow cover while not present in the first two gondolas, is not unusual. Most are blue, but green is seen in Venice as well.
The deck trim was what first caught my eye - there seems to be an additional trim line within each flat deck surface.
The second thing I noticed was how the trasto-da-prua was not carved in the usual way (with carvings that stretch from rail to rail), but instead, there was a medium-sized crest carved at the peak with the rest of the trasto left plain.
The ferro was missing one of it's three decorative pieces, but that's about as common as a boxer with a broken nose.
This gondolier emerged from under the bridge, interacting with his passengers and pointing to something ahead. He was wearing a white overshirt and sunglasses.
The fuzzy fringe of his seats was faded a bit - this frequently happens when you leave the black-fringed seats in the sun too much (I learned that the hard way).
Lately I've noticed spare remi aboard a lot of the gondolas I've seen in Venice. They may have always been there, but they are a new target on my radar.
This guy had two of them, tucked neatly under the deck - you can just barely see them between trastolini and deck behind the gondolier.