Social Networking Sites and Your Career

I mostly post about fitness and nutrition, but I do post about 'lifestyle' too. Considering how popular social networking sites are these days, many people don't seem to realize the downside to sites such as Facebook. 
I'm 23 years old, and I like to think of myself as grown up and mature, and I also like to think that my social networking pages reflect that. Over the last year I have tweaked my pages so they come across as more 'professional'. Why have I done that? Well, this year I have started my own business (actually started it so everything is in place for the future, rather than 'full on' now...) and I talk to clients, other companies and people that I network with. If my Facebook, Twitter or Linkedin pages made me look immature and stupid, that is the impression others will have of me, which is obviously a bad thing! I've also added custom content such as cover photos to give them a personal touch.
Being 23, I am still young, but that does not mean I should act young. I know many people around the age of 23, and some of them have social networking pages that are rather embarrassing to be honest! 'Liking' pages that are either controversial or obscene, posting status's and pictures that should be kept private etc etc. I have come across people that work in a professional environment and have ridiuclous status's, which brings me onto this.... status's....
If you don't like your job or boss, that is fair enough, but don't go and slag them off on your Facebook or Twitter! Employers now, more than ever, go onto their employee's social networking pages, and if they see obscene things you have written...well...it doesn't look good! Especially if you are in a job that revolves around meeting new clients, because if those new clients search for you over social media, they will see the type of person that you appear to be! People have been fired because of what they put on social sites, there has been articles in many popular magazines about the 'do's and don'ts' of social media, so it is actually a serious thing. How would you feel if you lost your job because you couldn't help writing something bad on Facebook?...
Obviously it does depend what industry you are in, but I think its wise to appear mature and grown up regardless what your job is. Myself and many others that I know have deleted a lot of people from Facebook because of what they always put on there, it's just annoying, like they haven't grown up since the age of 15! Those people just don't seem to see what they are doing. If you are someone who works in a bank or a similar job, which is a very professional environment, by having tons of pictures on your Facebook of you getting drunk out of your mind, and status's always referring to going out getting drunk - do you think that suits your job? no, will it impress your boss? no, will it impress potential clients? no. A lot of people nowadays who are going to meet people for their job, search for them on Facebook, Twitter and Linkedin, I personally do. They do this so they have a rough idea who they are about to meet and talk to, and what kind of person they are. Just imagine if you were trying to land a client, and they search for you and see tons of pictures of you drunk and always moaning about your job and boss... don't be surprised if they cancel the meeting! 
Everyone has a personal life, and everyone has the right to do what they want with it, but you really should keep your personal life and business life separate. Be careful with what you post over the web, what pictures you upload, pages you 'like' and so on. This can really help improve your image, which in turn can improve your career.