The two of them suddenly stopped, tilting their heads back and nostrils flaring. The sight caused Applejack to tense. Was it possible? Could they smell her masculine arousal? If so, did the two of them recognize it?

Considering they're character tags, yeah.

"Eyup," Applejack said with a sigh, not sound very happy. "'though it don't look like the cure worked any. Still got this thing and all."

Well, it isn't pure Poison Joke.

Good thing her fillyhood friend Coloratura is paying a visit to see Applejack......oops.

It's pretty obvious what's happening. Applejack's desire prompted by the Heart's Desire plant is to have a large family of children. The Poison Joke made her a sex goddess to facilitate that but twisted it slightly making her the ultimate father rather than the ultimate mother with powerful pheromones that give any mare that scents her a powerful lust. Heart's Desire has mind altering properties and its magic grows stronger with time (as seen with the cutie pox). Which is why AJ isn't fighting her new desires very hard despite the odd behavior of the mares around her (and the sex pheromones make consent kind of questionable). The only good news is that mares seem to snap out of it after being inseminated by Applejack.

Speculation: If Applejack isn't cured soon her pheromones might grow in strength to blanket all of Ponyville resulting in a mass orgy and every sexually mature mare in town pregnant with her foals.

7455157 Somehow, I never actually saw that line... I'm not sure why, but all I read seemed to ammount to her leaning against the table and getting a warning not to... maybe I was just drowsy still and glossed over one of the lines XD