I am mostly impressed with how well non-native english speakers post here and elsewhere on the WWW. In general the inadvertent replacement of words with similar sounding substitutes is a tell, that the person is not a heavy reader, so is only familiar with the phrase from hearing it spoken. Amusing perhaps because the substituted words have different meaning, suggesting that the mis-user doesn't really understand completely the phrase he is trying to repeat.
I am not above making my own mistakes, but I have one personal peeve, the misspelling of the word "bus". Unlike most incorrect word substitutions that are (IMO) caused by not seeing them used in print, the affectation to use two 's'es, has gained traction precisely because it has been seen misspelled by some high profile companies, in advertisements and literature. This misspelling/misuse is not caught by spell checkers because 'buss' is a real word, albeit with a completely unrelated meaning. Perhaps if enough people spell it wrong (use the wrong word), it will become the new right use. I'll hate that too... :'(
For common mistakes I will either try to correct people off list, or just use the word spelled correctly in my response. Sometimes when the mistake is in the topic of the thread. it just gets automatically repeated, over and over, like waving a flag to draw attention to itself. I suspect some people are already tied of my whining about bus(s).
JR
PS: For extra credit count all the mistakes I just made in this post... but don't tell me. There is no prize.