not a pretty sight

(idiomatic, by extension) Something disappointing, disquieting, disreputable, or otherwise unworthy of admiration.

Example: 1890, Sir Arthur Conan Doyle, The Firm of Girdlestone, ch. 44:
  The navvy was certainly not a pretty sight. His muscular arms and legs were all a-sprawl and his head hung back at a strange angle to his body.
1918, B. M. Bower, Cabin Fever, ch. 11:
  Bud was not a pretty sight. Four days and nights of trying to see how much whisky he could drink, and how long he could play poker without going to sleep or going broke, had left their mark on his face.
1909, Jack London, Martin Eden, ch. 35:
  Her lover, cheek by jowl with Maria, at the head of that army of Portuguese ragamuffins, was not a pretty sight.
1929 June 23, "Impelled to Passage," Time:
  The Tariff Bill was rounded into shape for final passage by the House last week. It was not a pretty sight for soft-hearted political theorists.
2002, Simon Szreter, "The State of Social Capital," Theory and Society, vol. 31, no. 5, p. 597:
  They showed little remorse in using this power to its full extent, against each other, against smaller producers and against the laboring poor, including strong-arm tactics of no legality. The result was not a pretty sight.