Interpretting a low Aggression Factor

Last night I was playing on a table with a loose passive opponent seated to my left. In the first 50 to 100 hands, I ended up losing a fair amount of money to this player simply through failed bluff attempts.

It seemed like every time I raised to enter the pot, this player would call me (turns out he CC'ed 60% of the time). He'd then follow me to the river no matter how much strength I showed or how scary the board became (turns out he only folded on the flop or turn 8% of the time but was much more wary of calling on the river - folding 60% of the time).

Even with a VPIP of 60%, he was often getting to the river with a better hand than me and taking the pot down.

Unfortunately for me, for the first half an hour, I was playing this guy on the assumption that an aggression factor < 0.5 indicated a "weak" player and "weak" meant they would fold if shown aggression.

It took a 20BB downswing for me to re-evaluate this assumption!

I reminded myself that aggression factor is the ratio of checks and calls to bets and raises. This guy was a calling station, not a folding station.

he was cold calling a tight player with a wide range. He failed to extract any sizeable value from his strong hands (calling down top pairs, two pairs and even straights). He played pocket AAs like a maniac regardless of board texture or opponent behaviour. I could tell he was a bad player but my blinkered use of the AF stat led to spewing chips his way.

Thankfully I did adjust and claw a little back but it was hard to build big enough pots to make a full comeback and to add an additional complication, a solid regular (Dilan12) turned up later, sitting to the fish's immediate left. when I got up, I was still 14BB down on the session.