Some textures used for signs have horizontally flipped UVs when the signs are viewed from certain angles so the text in the images doesn't appear mirrored and backwards. These textures are:
sign-arrows
sign-baron
sign-blank
sign-crimson
sign-ctygenb-erol
sign-ctygenb-praxis-banner
sign-doctors
sign-erol
sign-fashion2
sign-future
sign-gt2
sign-happy-pirate
sign-hiphog
sign-hiphog-slumc
sign-hiphog2
sign-hiphog-exterior-chick
sign-hiphog-exterior-krew
sign-holding-right
sign-krew-international
sign-loading-left
sign-m5
sign-metalhead
sign-naughtydog
sign-no-unloading
sign-onin-knows
sign-praxis-banner
sign-vert-right-arrow