I honestly don't think (here in Scotland anyway) that the word Scotch falling out of favour had anything to do with the stereotype of the mean and miserly Scot. It was a general Scottish stereotype and not restricted to the word Scotch. These stereotypes are diminished from what they were but here in the UK two general stereotypes were/are that the Scots are miserly and mean whilst the Irish are thick and stupid. It is still quite common here in Scotland to hear someone say "how Irish is that?" if something appears daft or doesn't make sense. I agree it doesn't mean people saying it are anti-Irish but it is a targeted stereotype none the less.

When I was young it was quite common here in the Scottish Borders anyway to hear mean or miserly behaviour being described as Jewish! Indeed there is a high road near Jedburgh from where you can view the rugby ground without paying and it is was referred to as the 'Jew's Gallery'. And the term "play the white man" to mean act fairly - as if not whites would not act fairly. Folks would generally keep well clear of using these nowadays. I suppose because Scots aren't an oppressed minority like these other groups then the stereotype appears softer and non sinister! Scots in general would just laugh it off - and within Scotland we have the same thing where Aberdonians are stereotyped as miserly.

I honestly think that the word "Scotch" fell out of favour from the 1920s and afterwards because of the Scottish Literary Renaissance where native terms were applied more - and writers in general and probably later the public came to view the word "Scotch" as being more of the kailyard, associated with twee Brigadoonery etc.