The ones that peak at #1 in their debut week, but then drop like a rock. It's one thing to stay consistent but the songs that notably drop after peaking at #1 for a week are embarrassing.
Touch My Body, Crack a Bottle, 3, Hold It Against Me, Part of Me, PillowTalk
The ones that are HEAVILY, heavily influenced by their inclusion in "viral videos", but lack sales or radio play
Harlem Shake being the most obvious. I remember there was this one song that was in some "strangers kiss strangers" video that went viral and it debuted at 9 and then completely fell off the chart a week later. a MESS. I've always had a lowkey hatred for Billboard when they heavily incorporated streaming into their methodology. Songs like "Watch Me Whip/Nae Nae" stay in the Top 5 forever when they lack sales.
The ones that use rent-a-rapper tactics to snatch the #1 for a week or two
S&M, Last Friday Night, Bad Blood, E.T.
And the ones that are just freaking terrible and don't deserve it because they're awful songs
Work, Cheerleader, Rude, Whistle, Black and Yellow, Crank That Soulja Boy, Laffy Taffy (this one is the most tragic tbh

), Grillz (who even remembers this song)???