It's quite scary when you realize how many germs are lurking in the gym. You can understand why though - lots of people sweating in the gym, not all of them wiping down equipment, if someone has a cold that can so easily spread etc etc.
A lot of gyms now have a policy that you have to bring a towel with you in the gym and wipe down the equipment after you have used it, so others don't have to sit/lay down in your sweat - that should be a must in every gym!
How to help keep germs away?
To start with, as mentioned above, take a towel with you (preferably a smaller one than your bath towel) and use it to lay on/sit on when using equipment and to wipe down the equipment. This will get rid of your sweat so someone else doesn't have to come and sit or lay in it. If you are feeling under the weather, it's not always wise to go the gym and workout, sometimes its best to stay at home and rest. If your ill and you workout, it can pump the virus around your body faster and end up more ill! believe me, that's happened to me before! An obvious thing to do, and if anyone does not do this, what the hell is wrong with you?? wash your hands after using the lavatory! and, depending where you have come from (you may work at a job that you pick up germs on your hands) wash your hands before entering the gym. I have even seen guys sneezing over gym equipment! that's just disgusting... respect the equipment and those around you and you will not only have a better workout, but you will be healthier too!