do you not have a contract that spells out your duties? you say you don't 'feel' you're there to clean. that signals to me that your arrangement is far too fuzzy.
it's not hateful to be courteous and clear about your expectations. you don't have to present it as 'clean up, you pigs.' how about if you just stop cleaning?
you've set yourself up to disappoint them since, apparently without agreement or instruction to do so, you 'cleaned it all to perfection' early on. so now you have to face it- you either need to have a conversation with them (preferable by far) or educate them through your actions (or in this case, non-action.)
if you need to make a meal for the children, clear a small space on the countertop, wash exactly as many dishes as you need to prepare a simple meal, and clean only them when you're through.
take sanitary wipes into the bathroom so you can have an appropriate seat on the commode and de-gunked sink to use, but don't clean beyond what you have to touch.
it would help a lot to know just what the agreement was, even if it was only verbal.
it would help even more to have a calm, non-accusatory, clear conversation with your employers so everyone knows where everyone else is coming from.
if they want you to clean and are willing to pay you more to do so, is it something you'd consider?
we had a nanny after our mom died when i was a kid. her contract spelled out clearly that she was only expected to do 'light housekeeping' and only that which directly related to child care. since my dad had never cleaned a thing in his life, he did leave it all to her, and she did do it. later, after they were married, they laughed about how badly she was taken advantage of, but in retrospect it wasn't funny at all.
your employers shouldn't make you guess what your duties are. you shouldn't make them guess about how much you're willing to do for whatever you're being paid.
sometimes you just have to suck it up and have a frank conversation. if you have good manners, you don't have to be hateful about it.
khairete
S.