Graffiti is it good or bad

Graffiti- is it good or bad?
----------Graffiti in todays society
Being a usual traveler on public transport I have always appreciated things to look at out the window。I mean let's face it,catching a bus or a train isn't terribly exciting is it?One of the things that always seem to be changing is the graffiti which is scattered along the railway lines。I don't know why it interests me so much,but the artwork behind some of this graffiti is rather well done。
I'm not supporting the use of graffiti。I can't imagine the annoyance of residents having repeatable having their properties vandalised with spray cans。Despite this I think these people are creating art and that us as the traveller are the audience。These people only wish recognition and by doing so expect nothing for it。When I say this I am talking about the good graffiti artist。I call these people artists because of what they can achieve requires talent and hard work。I am not talking about 90% of these 'artists' because scribbling an unreable 'tag' on a wall is not art。It's bad enough some have to do it once in the same vicinity let alone a few times。
Again,I realise graffiti is considered vandalism and this is dead wrong。I also know that the council's job is to clean up graffiti,good or bad。I guess you could say I have some confusion over this to why graffiti artists target areas where they know it will be soon removed。
I don't know anything about this have a case here,but it also interesting the areas of graffiti appear。Some walls appear completely blank,yet others are crammed full。It almost seems like a alliance has been setup between houses & companies and those who do 'tag' them will be punished by other groups。Is this all random or does there really exist a system of territories and safe places to graffiti?I don't pretend to know this or not but the thought of it does interest me,especially when I see certain tags standing out from the rest with generous space around it,despite having plenty of room next to it for more tags。
To sum it up I find graffiti strangely interesting,and with the rare chance of being impressed by seeing what can be achieved with some aerosole cans。It is something that a lot of people frown upon and is quite possible more complicated than it really looks。I'd love to see all amatuer graffiti 'artists' or vandals stopped by having 24 hour surveilance and instead hire proffessionals to really create a visual artwork for all those weary travels like myself on the mundane public transport system!