Open communities like reddit can be extremely kind, productive and helpful. I have seen many examples of strangers reaching out and helping people in need.
At other times they exhibit the worst that humanity has to offer!
It really depends on where you are posting and who the first person to see your post was.
More often than not, the first response can set the tone for everything that follows.
Personally I dont post on reddit much anymore. I used to be extremely active on it, in fact the only reason we are named "TEST" is because of a reddit post (Im making a video on that today).
A big part of what you can expect depends on the attitude of the mods and community leaders. When they give the worst elements too much room, the entire sub devolves towards the lowest common denominator.
Put on too many rules, the sub rebels.
Its a fine balance they try keep.