Awesome - thanks for the comments. I love this type of feedback - basically, I am not a people person - and this shot was more of a passing shot as I rushed by - hence no composition or real care etc - however, I personally liked it enough to keep it - my only curiosity was color vs black/white as I am colorblind and, well, am not good at these judgement calls.
As for the issue of exploiting - no, I don't think I am, nor do I worry about that type of thing.
Example 1)
Let's say that you were leaving a theater and, inadvertently, you kicked someone in their shins.
When that person says 'ouch', is it up to you to say that the kick didn't hurt enough to warrant the 'ow.'
Example 2)
You are sitting at a wedding reception taking casual shots and your beloved, hefty niece falls on the dance floor revealing that she is barely wearing thong underwear
Her entire but is exposed to the crowd and to your camera.
Would you take a picture and post that on the Internet?
You aren't the best person to judge whether your actions were exploitation.
You have to accept that not everyone wants their state to be exposed to the world - the homeless are particularly vulnerable because they really don't have any place to hide.
If that homeless person were your father, brother, son, nephew, I would hope that you would be compassionate enough about them to respect their privacy and not expose their situation any more.
You certainly aren't telling or showing us anything either new, interesting or educational; certainly nothing that would justify violating what little privacy this person has.