To the (manager?) of the Royal Farms store in Gamber, Maryland: If you have a problem with a female customer leaving the bathroom lights on at your store, simply ducking in and switching them off will suffice. There's no need for a snarky "Electricity is expensive, you know!"* I'm well aware of that. But given that probably 15 seconds after you switched off the light, some other woman will probably switch them back on again, and given that turning the lights on and off multiple times in a short period of time will decrease the effective life of the light bulbs in the bathroom, I think it may be more expensive to keep switching the lights on and off. For want of putting in a motion-activated light (you know, like the motion activated water faucet and the motion activated paper towel dispenser you already have), you insulted a paying customer.
Oh, and bucko, I realize doing inventory on the candy by the front counter is necessary, but maybe not the best of ideas when you have a long line waiting to pay, so you're trying to work in the same several square feet of floor they have to wait to pay. Maybe it'd be a better idea to work on that when it's not quite so busy? But if this is the only time you can do it, saying "Excuse me" to the customers you bump into would be a nice gesture.
To the clerk at the Walgreen's drug store in Eldersburg, Maryland. If you are closed for set up, perhaps customers bugging you to come in might go away if you put a sign on the door saying "closed." A sign saying "Walgreen's welcome's (sic) you, Monday, November 26, 2007" is a little cryptic for what you want to convey. Otherwise customers are going to look to the sign to the left of that, the one that says your Sunday hours are 10 to 8, and think WTF?
*I'm aware of that, seeing how I pay my own electric bills. But if I'm having a party, I tend to leave lights on for my guests.