". . . all I see is trash"oooooooo that's a bit harsh, aaanyway.Scoots was unconsciously manifesting her Rainbow Dash fears as the headless horse. Thus the horse was hurting her psychologically.

Scoots was unsure whether or not to heed Luna's advice. Then after she woke up, even though Luna blasted it away and got her to understand that that wasn’t what she really feared, Scoots was still afraid of the headless horse cus ya know she’s a kid and kids have trouble thinking rationally.

As for eventually having no option but to come clean to Rainbow, I doubt it, if it wasn’t for Luna talking a bit of sense in her, after gaining a bit of her trust by symbolically saving her form the horse; I think she would have continued lying to everypony.

There’s a reason why so many of us in the fandom call Scoots a chicken and the reason isn’t as shallow or narrow-minded as many may think.