Strange...... after reading this thread, I find myself in a distinct minority.
I have DMed for 26 years, and I have been a player off and on (more off than on) for the same amount of time.
I have absolutely no trouble taking off my 'DM hat' and putting on my 'Player hat'.
I realize that whomever is DM will have his own style and his own way of doing things. Including, different house rules, sometimes.
That is absolutely fine - I don't want 'DM - Attack of the Clones'.
Maybe my attitude comes from fact that when I am the DM, the game runs by my rules, my style of DMing and I expect not to be questioned or called to account by the players on every difference of opinion.
As a result, when I put on the Player hat, I automatically extend that level of respect to the guy on the other side of the screen. It is his world, his rules, his style of DMing.
And I don't have any problem with it. I can completely divorced myself from making conscious or unconscious comparisions with the way I run my game to the way the other DM runs his game.
Which is why I am amazed to find that in regards to the people who have posted so far on this thread, I am in a very distinct minority.