Not using air freshener

Air freshener is there for a reason: to freshen the air after you use the toilet. If you’re not using it, you’re not doing your part toward making the next person’s bathroom experience a positive one. Neglecting to use the air freshener is one of the many broken rules that prove you’re not a good house guest either.
Overusing air freshener

Yes, use air freshener. But no, don’t overdo it. The next person to use the bathroom should be able to breathe without getting a lungful of canned, scented air.
Not changing the toilet paper roll

If you leave the bathroom with the cardboard showing on the toilet paper roll, then you’re not being considerate to the next person to use the bathroom. If the toilet paper runs out while you’re using the bathroom, it’s your job to put on a new roll and throw the empty one in the trash. When you’re in a public restroom, let the appropriate person know it needs to be replaced (i.e. bathroom attendant or restaurant manager).