3 months? 6 months? Over a year? Not sure you have done it since you had the kitchen re done 6 years ago?
Well I have just three words to say about its probable contents.....
rancid fat globules
I have smelt and seen many bad bad things in my life (including a goat during post mortem, and wet gangrenous toes). This may beat them to the top of the list of things that make me go 'ugk memrmr oh bleeeerrk eckkkkkk'.
Go and replace it now. You know you need to.