Asslamo Allaikum,
According to research of some scholars such Shaykh Abu Ameenah Bilal Phillips [His Thesis which is available as a book on the subject] (& others) around the world it can be ascertained that Jinns do live in Dirty filthy Places and that is may be why the DUA for entring the toilet is
"In the name of Allah: OAlláh, I seek Your protection from male and female devils. (Bukhari)"
Arabic, Transliteration & Translation available at:
http://www.central-mosque.com/Dua/3.htm
When you read Shaykh Abu Ameenah Bilal Phillips's thesis & there may be some indirect evidence in the matter that Jinns do get disturbed by creating hostile environments (i.e. pouring hot water) in their habitat (toilet etc.) but please note that the evidence just described in "inferred" & not "directly drawn from the Qur'aan & Sunnah"
If any of the more knowledgable Brothers/Sisters are aware of direct evidence then please feel free to overwrite what I have written Insha'Allah...
Going off the Tangent...
In my personal experince of dealing with Jinns (perhaps to be precise suspected cases of Jinns) the state of cleaniness of the patient/habitat & habits is a definite factor...so I am unable to back it up with evidence from Qur'aan & Sunnah but cleanliness is a factor in my "personal experince" so I would avoid such unnecessary practices (hot water etc.); if they are necessary then take precaution & I would always read the duas of protection when going in a Toilet & so on
In Summary we should base the Qur'aan and Sunnah as our guide in everything and not anecdotal evidence as I know people in UK are grabbing money off people are advising all sorts of hocus-pocus (excuse the Pun!)
Jazakullah Khairun
P.S: Shaykh's thesis is listed here:
http://www.dukandar.com/jinn.html