Okay as someone who has relatives and friends who work in the music industry from various genres (ethnic, rock and pop) I will give my examples based on conversions I had with them about Eurovision since the jury result should in practice reflect their opinion:
Worst Decisions:
2013: Killing
this one came as a surprise to me since pretty much all of them dislike rap music (they don't hate it) but for my surprise they actually liked igranka.
2014: Allowing
to win and not placing
first I know this a controversial opinion but pretty much every musician I know saw "Rise like a Phoenix " as a stereotypical Eurovision ballad while "Calm After Storm" broke expectations on what a Eurovision song is.
2015: Putting
outside the top 10 out of the class of 2015
was among the most liked songs among the musicians that I spoke to so it comes as a surprise to me that the juries would rank them so low.
2016: Not ranking
first, for many of them especially the ones that are involved in ethnic music "1944" is their favourite Eurovsion song.
2017: Putting
outside the top 5 I know she didn't give the best performance, but none of the musicians that I spoke to noticed that and still had "City Lights" among their favourites of 2017.
2018: I don't know what to make of this, some of them really hated
while others found it fun and innovative.
2019: Not ranking
first.
Best Decisions:
2014: Ranking
among the top 10 I don't want to repeat myself.
2015: Making
win I know a controversial opinion again but "Heroes" was actually among the most successful Eurovision songs here.
2016: Making
not win controversial opinion again, but they all saw "You're the only One" as an irremediable Eurovision song that has no qualities outside the bubble.
2017:They all liked
so it was nice to see it score so many 12 points.
2018: Putting
among the top 10 while some of them did have "Nobody but You" as their number all of them agreed that it deserved to be among the top 10.
2019: Placing
among the top 10 I don't know if its patriotism but all of them liked "Proud" even before the live performance.