I take it by the reference to her saying Lou had pockets full of cash and that Junior had liked him, that he wasn't a "straight shooter" ?

Junior plays it off by saying someone has to win at the track.

I still think a prequel could be cool from Juniors days.

I'm thinking Lou was on the payroll, and Junior tries sugarcoating it because he doesn't want to hurt Catherine Romano's feelings nor her memory of her late husband.

You can see it in the hospital scene (where Junior and Catherine reconnect and Junior is a pain in the ass to the nurse), where the son rather curtly cuts off the conversation, claiming he has to go make a call. I think the son knew what the old man was up to.

Yeah i forgot about that, the son was a cop also didn't Catherine say ?

Looked like he didn't like Junior, obviously knew what he was about, although i wonder if he knew he and his dad had business.

Yes, the kid was a cop. A detective, she points out.

Between her pointing that part out, the chilly look the kid gave Junior, and the money comment later in the episode, I got the vibe that Lou was a uniformed officer on the take.