In reply to johncoxmysteriously:
SERIOUS ANSWER!
I thought I'd better put that in bold and capitals, so that you might see it amongst all the crap.
Once the cat has sprayed in a particular place, in this case your toaster, the smell will remain (to the cat's nose), even after you wash the area and it will think that the area is the correct place to piss.
What you need to do is to wash the area with soap and water and dry thoroughly. Then, spray the area with surgical spririt and let it dry naturally. Thirdly, get yourself some of this stuff:
http://www.vetuk.co.uk/index.php?main_page=product_info&products_id=333
and spray the area with it. What this process does is to remove the smell, even to the cat's nose and the feliway spray mimics a cat's facial pheromones. Cats won't piss where they rub their faces. You might need to repeat this process a few times, but it does work and it's cheaper than constantly buying new toasters.