there are 2 factors.

first - there are 20 million + people on here so if just 1 in 20 million people does not like your comment then you get down voted.

second - reddit has a bad habit of up voting or down voting according to how they like your user name. the trick is to keep creating new accounts and test how they like your name. i have over 100 accounts now and i know this for a fact that some names reddit loves me, other names the account goes nowhere. as an example im /u/lightning_round , /u/white_punks_on_dope , /u/live_wire_shock , /u/gonna_start_a_riot , /u/trailerpark_boy , /u/call_me_lucifer , /r/tornado_sam

i switch when i feel like it , im the same person but each account is treated differently according to how the people of reddit perceive me as that nick.