I actually found Ferengi Love Songs not that bad. It's definitely weak, but that's all. I wouldn't call it bad, and it definitely wasn't painful for me to watch; just boring. There are only 4 DS9 episodes I would call bad, namely Meridian, The Muse, Let He Who is Without Sin... and The Emperor's New Cloak; and of those two actually have enjoyable B-plots. The A-plots of these two, and the other two episodes entirely are just painful to watch. I'd probably give Ferengi Love Songs two stars, or maybe 1.5, myself.