Yes, of all the people quoted in the article, Kevin stuck out for me too. If you've arranged to go out for a walk with someone and on the day it's absolutely heaving it down, just meet for a coffee instead. It's not rocket science!
I got commended by a close friend recently for always honouring commitments. It is important to me to keep my word as integrity takes a long time to build, but can be demolished quickly. However, no one has ever commented on it in the past, I think it is becoming a rarer quality!
Regarding getting a better offer: I have a rule to stick to the event first agreed to. There has been the odd time where I have had to renege on an arrangement, but we're talking about being offered a free holiday versus a weekend away with friends. Plenty of notice time to rearrange the latter, and abject apologies. Being good friends, they understood.
To the poster who said none of her friends are flaky, you are very fortunate.