OK, I've watched a couple of $100/$200 NLHE cash games before, and it can be pretty straight forward play. I would estimate about 90% of the hands I watched had one bet and all folds, or even all folds to the BB. I left understanding why this was happening, but fairly bored.

Last night I watched a $5/$10 NLHE cash game. The problem was the hands people bet, raised and won with were absolutely crap. There were 7 people playing at some point so it wasn't like a heads up. Some examples of hands that were raised preflop include T8 suited, T6 unsuited, 64 unsuited. And these hands were both winning and losing hands, but betting/raising to showdown with pots up to $700, which was won by T6 when it hit a full house. The only decent cards I saw, was when two players both hit JJ and shared the pot. The players eventually all left only a few hands after the $700 pot.

I have a few theories, but hoepfully people here can enlighten me:
1. I am far too new to poker to understand the way these guys play poker. Tight/aggressive is great for new players, but pros have to play other hands to win from other pros.
2. A couple of players were playing loose so others joined in the game.
3. One or two players were trying to setup a loose image, before taking people to the bank with AK, and in the mean time got lucky with crap cards. I like this theory the best.
4. All mucked hands were actually AA or KK and the crap players betting crap cards lucked out every time.
5. These guys are happy to lose a couple of hundred dollars on losing hands in order to win a huge pot with a flush or 2 low pair when AK thinks nobody has anything more than their K.

To make matters worse I started playing a few flush draws and low connectors after this on a 1c/2c game thinking maybe it is a way to cash in when no high cards hit, but I failed miserably as I couldn't work out quite why I was playing them, and lost when I thought they'd hit well. Once I went back to tight aggressive on the next table I did OK.

Can someone please help me work out what happened there?

prolly a combination of 1, 3, and 4