Ach it is very much of its time. There wasn't much, if any, ethnic diversity in Glasgow (and much less in the wider central belt) at the time, and using epithets such as "chinky" or "darkie" were considered as acceptable, if slightly uncouth, descriptives. Considering the other, less savoury (to say the least) racial lexical territory being explored in the 1960's and 70's it can be seen as mild. It's easy to judge things by today's standards, but I think that consideration has to be given to the culture, time and place which produced the comedy. I don't have the same affection for Francie and Josie, but some of the jokes are very good. Rikki Fulton was an absolutely fantastic comedian too.
Tam Cowan has been preparing, in the method style, for the role of a 60 year old man for the past couple of decades. It seems like the role he was born to play.