Advantages of showering in the morning:
Advantages of showering in the evening:
Seems like a matter of personal preference.
Morning. I feel greezy the next day if I shower at night. Also, my hair will absolutley not behave right if I don’t fully shower it in the morning even if it is just for one minute. I have tried running sink water over it for 5 minutes with shampoo and everything and I still look I went straight from a bar to work.
Copout. Just because some people do things differently doesn’t mean that one group is not 100% wrong and should be notified of it. It is the essence of the boards.
Don’t people sweat a lot while they’re asleep? In my opinion, showering in the morning makes more sense.
I always shower in the morning because my hair is very long and thick and takes 3+ hours to dry. If I slept on it wet I would wake up looking ridiculous and just have to wash it again.
I sweat a LOT at night. I always shower in the morning. Unless I’m hanging out in my jammies all day, which I am wont to do on occasion!
Both. I’m a big guy with too many North European genes, and I live in the Middle East. Two showers a day are the bare minimum for civilized life.
Personal preference. In my case, personal inability to do anything that implies staying wholly vertical after 9pm. I can walk so long as there aren’s too many curves; I can sit; please don’t make me drive or stand in place.
You see, I’m a morning person. Yes, I know I shouldn’t. Sorry. It’s apparently genetic, several of my relatives are morning people as well. This doesn’t mean we go all chirpy on people who aren’t awake yet (unless we happen to hate their guts), but it does mean that we wake up earlier than we’d like to. Afternoon people spend the morning half-asleep and wake up sometime after lunch; I had a boyfriend who spent the morning like the living dead only deader, move to half-asleep about lunchtime and wake up about 6pm. Me, I wake up at 4am sun-time (so depending on the country it may be 5am or 6am, here in Costa Rica the clock actually goes with the sun the whole year round) and I wake up awake, completely unable to stay in bed any longer; in the afternoon I space out relatively easy; after dinner is… yawn… oh-hum, sorry… time to go to bed, yes?
So, for me having a shower in between taking off the pajamas and putting fresh clothes on is not a chore; having one between taking off the day clothes and putting the jammies on means danger of drowning.
Morning. It’s the only way for me to feel fully awake. I shave in the shower too. Always start the day clean, smooth and sweet-smelling. 
Evening for me. I can’t stand going to bed feeling dirty and sweaty.
Depends on the job. Back when I was digging ditches for a living I’d shower at night. No reason to clean up before going to work. Just slap on the hat and gloves and to to it.
Now that I no longer do real work for a living, I shower in the a.m., so as to smell pretty on the elevator up to the office.
Eww! Like it’s a choice? Twice a day, morning and evening. Hell, I’ll go for an afternoon spin on the weekends sometimes.
Morning. I get seriously grumpy if I can’t wash my hair every day. Makes camping difficult. I can’t wait to get an RV.
I get the worst bed-head in the world. I have to shower in the AM or face ridicule. 'Nuff said.
Full shower in the evening to get clean, and a quick, short rinse in the morning. And that’s only because I have a perm and I need to wet my hair and scrunch it. I don’t have enough time to take a full shower in the mornings. It’s nice to go to bed clean. I usually take my shower a few hours before bed, so I don’t have to sleep with wet hair.
Uh, ever heard of a towel? Do you NOT dry off properly or something? 
Ditto on that. I’m an office person, so I bathe in the morning. However, stinky, dirty jobs require after-work clean-up.
I used to shower at night. The warm (not hot & steamy) water didn’t wake me up; it relaxed me so I could go to sleep sooner.
Lately I notice that I wake up a bit sweaty, so I’ve switched to showering in the AM.
If I ever get my lazy butt back to the gym, it’ll be both.
It wakes you up? Pish! That’s what strong coffee is for.
Nothing more really needs to be said.
I shower whenever I feel inclined to be cleaner than I was. Usually if I’m working that’ll be when I get up (which isn’t necessarily the morning), but on my days off it can be at any time.