Okay, so I've played through about half the packs, and generally I start at 4 and go up and down from there. An atrocious level may still get a 2 from me, because I'm nice like that. However, a few levels left such a bad taste in my mouth that they got the "kiss of death". As follows:
Yoshi Coal Mine -- Flouncy Level 8
I found this level exceedingly dull and tedious. It's not complicated, but it has really no redeeming value. I've made plenty of levels like this and I'm not proud.
Water Slide -- Flouncy Level 44
These slide-type levels are not my favorites to begin with, but this one in particular is annoyingly hard. I think we do need some TORTURE CHAMBER-style levels, but not this one.
Finding -- Giraffe Level 18 and Puzzling -- Helmet Level 29
Okay, this was mostly just on principle. However, I have played these levels before and yes, I hated them then also.
Death Box -- Giraffe Level 32
Could not figure this out. Seems like a re-hash of "Commit Suicide?" with no solution. I'm sure it's there somewhere, I was just not interested in figuring it out.
Blocked Block -- Lipstick Level 13
This level is, for me, completely unsolvable. And not in a good MORTON "there's some trick to this right?" kind of way.
The Inner Plague -- Vermillion Level 23
OMG OMG OMG OMG OMG TEEEEEEEEETH!!!!!!
Flareon -- Dragon Level 6
Really? Pokémon? I mean, it's not even a fun level to play.
Teknopathetic -- Roadcone Level 42
Honestly, this is supposedly a great level. I could not get off the start tile in Lynx. It passed testing, so I'm sure it's possible, but if my old fingers cannot manage it, then it has a BA of 0 and that's just how it is.
In conclusion, I judge levels based almost solely on how I feel about them, rather than some external list of features or requirements. So, if you happen to make me ill, you will feel my wrath.