Here is a typical issue:
Simplify[x + y, x = y] produces
Is there a way to detect operator
Set in assumptions and issue a warning?
As Mr.Wizard suggested it is possible to write a wrapper for
Simplify that will check the second argument. But since there are many built-in functions which use assumptions it will be cumbersome to overload them all. Maybe there is a more simple way?
$Prewhich checks for whatever list of patterns you create of stuff you want to be warned about. $\endgroup$