I don't need to guess, I have a standard line. May sound silly but it doesn't feel to bad to see how other players play without pre-empting them - anyway, I Bet depending on the board texture and depending on opponent!
without going into fairly obvious adjustments for different opponents here is board texture;
If there is a nice dry high-card T+ flop to represent I will bet it just under 2/3rds OOP, bit over 1/2 IP (Note if I do not have Ax I C/F maybe half the time on an A high board due to the larger number of Ax hands in their ranges over Kx etc)
If there are two highcards on the flop I look more closely at the opponent before deciding whether to bet. Increased chance of 2nd pair, set, Gutshot etc makes me look a lot more closely at how their range connects with said board. Needless to say If I deem huge number of PP's to be in their calling range I bet and get more folds than on a single highcard flop.
If the flop is uber-drawy or I cannot rep TPTK easily eg, 8h9hTh or 257 rainbow I stay away from betting and Check/Fold. I have recently been thinking however one of these is a leak in zoom.
The "bad flop to cbet";
edit; This is about the 275 rainbow but I wrote four paragraphs detailing my thoughts. Definately too much, I shall instead just summarise.
A lot of opponents in zoom are now folding too much at least on microstakes to cbets on these boards. Maybe the "its a bad board to cbet, he must have something!" effect. I'm guessing that stakewise people stop doing this in NL50 or 100 although I can't confirm anything as of yet.