There are the 'good-time' friends and ones that are there for you no matter what.Sounds like the ones you mention are just good-time friends. They say you know who your true friends are when you need them.... A friendship needs to go both ways.... (ahem) giving and receiving....
I do know the difference between good time friends and not.
This is what happened - about 3 years ago a couple who were our neighbours and close friends called off their imminent wedding. This was as much a shock to the bride as it was to us. They separated living accomodation and of course the jilted bride was very very upset - she hadnt seen it coming, they';d been together 3 years etc etc. I was on call for her 24 hrs a day - i held her hand through the whole business for months afterwards, took her out, neglected my own relationship to be there for her etc etc. And at the time when she was full of gratitude etc and said what a wonderful friend I was I said well I would hope that if I ever found myself in a similar situation i would really hope my friends would be there for me too.
So here we are 3 or 4 years on. She is getting married to someone else - is blissfully happy and considers it a blessing that she never married boy friend 1- which is awesome - I am so happy for her. We dont live near enough to be friends who see each other regularly anymore but we speak and email and meet upo every few months when she can drag herself away from future hubby. Thats cool - I know how it goes. However I email to tell her that I am moving out after 9 years with my bf - and she doesnt even bother to reply. So I text her with my new address - thinking well maybe she'll phone and offer me some support or comfort maybe ask if I want to go out and drown my sorrows or something. Nothing. So I catch her on msn - she says hi - doesnt even mention my life changing situation. So I bring it up casually - did you get my new address and she says "yeah and then along the lines of well it's probably for the best or something equally pithy and with no real thought whatsoever. And I am left wondering - how she would have managed. At the time when she got dumped her concerned and rightly so dumper said that a lot of her so called friends had abandoned her and could I take her under my wing a bit, which I would have donw anyway because I am like that.
So it seems she learnt nothing and is just as bad as her own fairweather friends. I feel a bit tee-ed off to not get any support at all from her. I have to say the rest of my friends have done what they can to be good to me and I'm really grateful for that. And of course you guys have all be spectacularly awesome and help me cope with the day to day by stimulating my mind, giving me ideas, taking me out of myself so I can think and comment on yoru problems, and making me laugh.