There have been times in my WoW career that I would much rather play in a group of pugs while listening to Celine Dion and snorting wassabe than play with a few of my guildies.
Pugs are temporary. If the people suck you never really have to see them again. They are disposable. Guildies are not the same. If you are in a guild you enjoy, you have to tolerate the "baddies".
I have been in my fair share of failpugs. When I hit 60, I put the fail into fail pug. I was told that I should tank and I thought.....what the hell is tanking? I have told the story of my first pug where my weapon broke part way through and I used a gray item in my bag.....that I had not leveled my weapon skill on. I learned from there and got much better over time.
I got into my first serious guild through pugging. I used to pug with the same people pretty much every night. Stratholme and Scholomance were usually on the agenda. I loved playing with these people and still play from them from time to time until this day.
There were a few in guild who were....well below what I was used to. One day, a friend from a former guild and I decided that we would run Scholomance.....me as tank and he as a healer. I brought along a few guildies. Two of them were bad beyond belief. One of them was a Mage that I previously mentioned that did 200 dps....at level70.......in epics. The other was a Hunter who was controlled by two people. A father and son. The son was pretty decent...the father was...not. Guess who I ended up with?
We basically wiped 5 times in the first and second room and decided that it as enought. The Hunter was pulling additional mobs with bad targeting and an agressive pet. The Mage was pulling other mobs as well. It was just embarrassing that I had invited a friend from the guild I left and we wiped 5 times in the very first part of the instance.
That is one of the reasons that I often choose to pug. If they suck, oh well. I dont have to see then chatter in green text and I dont have to deal with them. If a guildy is a retard, then you pretty much have to deal with it unless you want to find a new place to call home.
Enjoy your guild....but be sure to appreciate the value of a pug as well.