This topic led me to think about other common terms and phrases that we use without thinking and which are culturally offensive or at least insensitive. The first one which came to mind is "beat down by the man". We often say this (jokingly) at work when we mean that we are so jaded by the bureaucracy of management that we don't expect any real progress or change. Now that I am thinking about it, this phrase seems like a reference to slavery. I will use "beat down by the system" from now on (until I can think of something better)!

Actually, according to several sources “welch” is a variant of “welsh” and almost certainly does refer to the Welsh. The Welsh word for “Welsh” is Cymraeg, both a noun and an adjective. For a while, the term was mostly used negatively.