Not a pretty sight means it's very unpleasant and undesirable, which is what the context is describing.
Context: But everyone has the same, a slumping rotting figure and no sign of life, its unfortunate and very unpleasant.
Hypothesis: But everyone has the same, a slumping rotting figure and no sign of life, not a pretty sight.

Is the hypothesis incorrect? (Yes, no, or unknown)?