They should have all just got on the roofs and chilled...Plus it's already been proven you can wipe zombie guts all over you and walk with them no problem...
yes, in 'real life', all of them would just wake up each day, smother themselves in zombie blood, and never fear them again.
Anytime you're being chased by say, 1000 of them, you just run, smear blood, and voila, you walk among them.
i guess the show would get boring/gross if they were all smeared in blood, nonchalantly walking thru hordes all day