Flew DEL-SIN a couple of weeks ago, in J on an older A380. Acknowledging that my previous flight was in F, I still found this one quite poor.
I actually find the India-SIN redeye's probably consistently worst SQ flights I take, although usually DEL is a bit better as it leaves a little earlier and is a bit longer. I am not sure what exactly it is, probably a combination of grumpy passengers because of the hour, grumpy crew because of the hour, relatively short overnight flight, and/or the rather demanding nature of many passengers (that leads to a certain attitude amongst the crew). I also have a hunch these routes are the lowest down the pecking order= and get a greater share of less competent cabin crew, compared to other routes.