Maybe some clarification is in order... I've traveled in Mexico for at least one month for 15 out of the last 21 years. I've bought hundreds if not thousands of gallons of gas and diesel while here.
These past two weeks - 2,000 miles I have been cheated (attempted) twice at gas stations. Prior to that - the last 14 trips I was cheated once. I'm no statistician, but this year's experience was in my opinion noteworthy.
I never forget that I am a visitor here. I tip gas station attendants, wait staff, bus boys fairly but not excessively - to do so I have heard lectures calls attention to my wealth. On a motorcycle I tip the gas station attendants 5 pesos. Wait staff 20% Bus boys 80-100 pesos for bringing our luggage to the room.
Personally I trust everyone I come in contact with until there is a reason not to. I endure Mexican motorists who show little regard for my safety as they see how close they can get to my legs on the motorcycle. That's taken some work, but I am able to take it in stride... so to speak.
I'm not sure who the post a few posts back was directed at - just in case it was my comment, here's something to put in your pipe and smoke.