Personally can't recall ever seeing needles or human feces in or around Austin. Some areas/alleyways around 4th-7th can get pretty urine-y on the weekends.
Generally speaking, one is more likely to run into horse manure around Austin.
Was this down voted because the horse manure comment?
To clarify, I meant that quite literally. Horses are considered a legal vehicle. It is not uncommon to see people riding horses (small groups, solo, & APD mounted patrol) along the shoulder of a road or along the creek and river trails in central/south/southeast/east Austin, especially on the weekends. Probably other places too, but those are the areas I am familiar with.
It is certainly more common to see horse manure in the city than it is to see the human feces or needles that was alluded to in the comment I replied too. At least, in my personal experience spanning decades.
Generally speaking, one is more likely to run into horse manure around Austin.