The Fourier transforms map plane waves to points. Blocks of regularly-spaced text have a periodic character, with the period length of their line spacing; their Fourier transform (I think??) would, in 2d frequency space, have amplitude peaks on vectors that have the same angle as the rotation of the lines.
I think it's more typical to low-pass (i.e. blur) the image and then use a line-detection algorithm like the Hough transform. Properly deskewed text should have prominent horizontal white lines.
