A well-known phenomenon among ex-pats in Switzerland is the fact that the Swiss, who really are often multi-lingual, so often get it wrong when they think they’re using English words. One of the best examples is that a mobile phone is called a “handy” here (and in Germany, for that matter), which makes little sense to us – though since we don’t know whether to say “mobile” or “cell phone”… or is that simply British vs. US?! This and other terms of “Swinglish” are perhaps better xplained here http://www.newlyswissed.com/swinglish-101-the-swiss-say-the-darnest-things/ 
Handy is also the cult retro washing up brand for sale at Migros!! Since over 50 years (as a Swiss might say ;o)…
In turn, this means that the Swiss will sometimes use words incorrectly when they speak English, not realising the difference, and one I’ve noticed is “extra”. If you do something “especially” for someone, or “on purpose”, you did it “extra” (I know extra isn’t really English, but you can see what I mean, right?!). Children annoy you – it’s “extra”! Direct translation from German. 
A book that helps Germans to avoid misunderstanding the Swiss!
Another Swiss habit it took me a while to cotton on to and which I still don’t really understand (or ever remember to do) is the need to apologise before entering somebody’s home. Open the door, greet the visitor either with a handshake or three kisses on the cheeks (yep, three here!), depending on how well you know them, and then before they cross the threshold they will say, “Xgüsi…” (“excuse me” or “sorry” – a strange word anyway, neither French nor English – and certainly not German!) and sometimes again before entering your living room. I suppose Italians might say “permesso” or the French “permettez” for permission to enter, so perhaps it’s not all that different. It does still strike me as curious, though! A man come to fix something and wearing work boots will go through this ritual and then bend and take his boots off before coming to fix your electrics or your dishwasher, too :). Perhaps that’s the reason he needs to apologise…
The Little Wash-House 
I was wondering what X you would find! Xundheit! And I too have always been puzzled by the apology for entering your home, despite being invited in. An electrician arrived here (in the UK) with plastic shower caps that he put over his shoes on the doorstep – much easier than taking them off, and very effective. I was impressed!
I can remember asking you why someone entering my house used to say that. A certain relative used to do that all the time.
I remember, and I still haven’t found out why – I guess the Swiss are always trying to be hyperpolite…?!
Apologizing for coming to your house? That is a strange one. We have no traditions like this to compare. The most common is to say hello to a guest and open the door for them to enter. Pretty boring compared to your ways.