If you roll your toilet paper 'over' instead of 'under', you're doing it wrong. I don't say this out of subjective sentiment, but out of pure logic. Put frankly, if you roll your toilet paper overhand, you've lived as a second-class citizen your entire life, and you'd be better served using old newspaper than your fancily quilted Kleenex. In fact, the only thing more frustrating than people who roll their toilet paper overhand are those who finish a roll only to leave a fresh one sitting on top, forgoing the five seconds of courtesy required to actually replace the empty roll with the one already in their hands. Lifehacker had a recent post on this very subject, and some of the responses are nothing short of hilarious. Going by the comments it seems that some people who roll toilet paper overhand do so out of sheer laziness. For example:
When the roll is backwards, the paper hangs down against the wall, probably 4 inches FURTHER away [4 inches?!?!]. To place that precious tissue any further away than necessary results in a possibly dangerous and definitely precarious lean, lifting the buttocks further off the seat and risking leakage or even tumbling to the floor...with even more serious leakage issues.
If toilet paper itself were nothing more than a flat sheet of paper, and were equal in appearance and texture on both sides, the over-vs-under debate would be infinitely more subjective. In that case there would be no correct way of using toilet paper, as the only notable difference would be the place from which it rolls. Unfortunately for the overhand apologists, this is not the case. Toilet paper is perfumed, patterned, and quilted, and the latter two features should, at least to the sensible mind, settle the debate for the rest of eternity.
Taking the above image as a prime example, consider that the softest side of the toilet paper is the side most exposed to us visually. As this roll has been correctly placed in the underhand fashion, when it is folded the softest side will continue to face outwards, resulting in a more pleasurable experience during its use. If this were not important nobody would care about double and triple quilting. And since we are making buying decisions based on quilting, which also affects the price, should we not be maximising its use? Using the flatter side of the toilet paper is as wasteful as it is thoughtless, and doing so should be a strict offence, like letting water run needlessly, and stalking little children.
If that's not convincing enough, consider that the patterns on toilet paper actually serve a purpose, particularly on coloured and decorated (as opposed to generically quilted) toilet paper. The point of decorating toilet paper is not simply to enhance the Feng Shui of your bathroom, but to better camouflage the results of its use. Few people enjoy looking at used toilet paper, and while decorating and perfuming it has a rather minimal effect, it does mitigate the grossness. Rolling toilet paper overhand leaves one with a deservedly unmitigated and visually displeasing experience.
Ultimately the most important thing to consider is the intention of the manufacturers, as they know toilet paper better than the rest of us. It is no accident that the softest part of the toilet paper is also the part that is decorated. Judging by its softness and colourful exterior, the outside of toilet paper is clearly the part manufactured for use, and it follows that toilet paper should always be placed in an underhand fashion.
Which leads me to ...
If you had shit on your hand - would you be satisfied with just wiping it off with paper? - an argument made in favour of using wet wipes
This is quite true, as faeces is one of the most repulsive things that we have to cope with as humans. It is unhygienic, it smells bad, and it is generally something we wish we didn't have to deal with. For the majority of people, getting faeces on their hands makes washing it off an absolute priority, and with good reason.
So why are we unhappy with getting faeces on our hands, yet we are willing to place our genitalia directly at the source? It's not okay to get it on your skin, yet it's okay to place your favourite body part inches deep in it, provided it gives you sexual pleasure? How does this not disgust you? What the fuck are you thinking?! How in the hell can you find the thought of it exciting?!?
I can see the counter-arguments coming already. There will be data about the number of bacteria found in female genitalia, and arguments as to how oral sex is terribly unhygienic, but nothing, and I mean NOTHING can be more unhygienic or filthier both psychologically and physically than activities involving faeces. You wouldn't go in to a sewer and splash about naked, yet you'd stick your penis in one if it felt good? And this makes sense to you how?
The real problem with anal sex is exactly in line with the rest of humanity's problems, in that we are selfish. We allow ourselves to become irrational in the face of impure desire. Our minds seek this sexual frontier, so the logic which would normally ring bells of disgust suddenly becomes an afterthought, and we roll with what feels good, not with what is good. Maybe placing your penis where faeces is expelled feels good to you, but I can't envision for the life of me how it is good.
Anal sex is disgusting, and if you enjoy it you seriously need to evaluate your own degree of self-centredness, and the extent to which you let yourself be overcome by your desires.