When there are no litter bins in an area (or if existing litter bins or full or broken) guests will throw their leftover food containers, papers and bottles on the ground as litter.
Litter can become a major problem in parks that are short on handymen and it can also be problematic to the happiness of your park guests. If there is too much litter in your park or in a certain part of your park, guests will become unhappy and will begin saying "The litter here is really bad." in their thought boxes. This will also greatly lower your park rating and can lead to an immense amount of messages concerning these problems through your message window. Be sure to deal with these problems when they arise and know how to prevent them.
Angry Guests / Vandals
In Roller Coaster Tycoon 1 and 2, Litter is the leading cause of angry guests, also known as vandals. When a guest walks through too much litter in a large amount of time, they will gain the special angry mood, which is characterised by a red, enraged face overlaying any normal moods in the guest's window. While angry, guests will seek out objects to vandalise, such as benches, lamp posts and litter bins. Vandalism can be prevented with well-placed security guards in areas containing the aforementioned items, although it is still recommended to assure that every section of your park contains at least one handyman to clean up any any litter, preventing these vandals from appearing, and it is recommended to place many trash bins near food stalls and bathrooms.
The above information applies to vomit, although litter bins will not reduce the amount of guests who will vomit in your park, unlike litter. Solutions to this are benches, which sick guests may rest on to recover without needing to vomit, and first aid rooms, which sick guests can visit for fast, vomit-free recovery.