Dirt and bacteria lurk where you least expect it. Apart from the risk of e-coli and other nasty bugs, your skin is being bombarded by unpleasant things from some very obvious but often not considered, places. Take your telephone (and certainly if you borrow some else's) unless you regularly wipe your phone with an antibacterial wipe, studies have found that mobile phones are contaminated with bacteria, even more than a toilet, which can cause breakouts and blemishes.
Mobile phones are covered with a combination of sweat, make-up, substances from your hands and germs from where you have placed your phone and these transfer to your skin each time you answer a call.
Another un-respected, though serious, source of problems is on public transport but none more so than on aircraft. Aircraft have to "turn around" that is, get one load of passengers off and a new load on, in about an hour or sometimes, even less. Cleaning after others is not always as thorough as one would wish.
Tray tables are not just used by passengers for eating. You do not know who sat on your seat before. Nappies may have been dropped on a tray table, dirty hands, books, tablets; tray tables are used for all sorts. Before you use a tray table, wipe it with a antiseptic wipe.
While germs in bathrooms might be expected, an armrest can hold even more E.coli bacteria. It may be even better just to let your neighbour use it, perhaps at the same time highlighting the germs that are present. Aircraft carpets are the worst. People (for some reason known only to themselves) choose to walk bare-foot about the aisle - even worse, to the toilet - UGH! It is, perhaps the best way to pick up infections known to mankind. And, of course, airline toilets are a nightmare. Always wash your hands after flushing, never before. Those armrests feature again; where people in the row behind then place their feet on the armrest in front.
Airline blankets are, at best, fresh for the first flight of the day only and more often, only washed once a month. Using an airline pillow should be a non-starter. What you have just placed over your skin has probably already been rubbed up against, wiped and sat on by any number of other people. After each flight, they are folded up and then reused. If you think you may need a blanket (or pillow) bring your own.
The air you breath on any aircraft (or indeed, on any form of enclosed public transport) is recycled much faster than in the great outdoors. Specifically on aircraft, air is bled from the engines as the aircraft has to maintain cabin pressure. Believe it or not, to save fuel, the air is recycled for much longer now than in times past, carrying with it the germs of all others. Further, the air is dry and is such as to wreak havoc on your skin. Carry a hydration mist at all times (in a less than 100ml bottle) and use liberally throughout your flight.
Finally, Your suitcase will be handled by many people when travelling. Pushed along conveyors, carted over many different floors and pavements. Never place your case on your hotel bed to unpack, give the handles, wheels and base a wipe down with a sanitiser. Even you hand-baggage will have picked up all sorts of bugs. Rubbing up against other bags in the overhead lockers (which lockers, are only given a bit of a wipe from time to time) and worst of all, if your bag has been placed on the floor, under your seat, where before, countless feet have been, both with and without shoes.
What may look clean, or worse, what you perceive to be clean, very often is not. What is not clean can affect your skin as much as make you ill. If you are ill, it is noticeable but there are long term affects on your skin condition which are harder to spot. Taking precautions and the liberal use of sanitiser on everyday objects, will help your health and in the longer term, the overall condition of your skin.