I've always defined an 8 in CHA as being how a geek comes across to a 'normal' person.
8 in INT would be a 'low average' IQ. Probably someone who could manage to get their ideas across well enough, but unable to use very large words. Someone able to do difficult arithmetic with a pencil and paper, and possibly the simplest algebra.
An 8 WIS person would be sensible, but unable to make long term plans and keep to them. S/he'd make reckless decision, and follow his/her heart rather than their head. Would be unable to break addictions such as nicotine addictions, even if they had the INT to know it is bad for them.
8 CON people are almost as resistant to very dangerous diseases as the average person (as they affect everyone), but would get more commen diseases such as colds and flu more often. Strangely though, it is concievable that since a low con person gets more diseases, he is therefore resistant to more of them...
With 8 DEX, this character was no gymnast. He could bounce a ball, but came near to last at the end of races. On the other hand, he could still dodge the odd ball coming his way.
The guy with 8 STR probably wanted an indoor job. He didn't enjoy lifting heavy loads, since he wasn't very good at it, but he could still bring in the harvest with some effort.