prosac forman oper labsand what you will get is searches that have results for :
prozac foreman opera labsnote that I'm not talking about the "did you mean" - I mean it silently decides to give you results for a different word. Awful.
Fortunately there is a trick to get around this. Just put your search word in quotes. Apparently you could also use a +, though that also makes the word mandatory.
See for example : here
It seems to me at least part of the problem is that the stemming is not aware of changing word meaning. eg. obviously if I search "widget" then results that contain "widgets" are probably good, but changing "prosac" to "prozac" is giving me completely unrelated results. You should only automatically broaden the search to word variants that are actually related.