Pigs are one of the cleanest animals and very easy to house train, they are also very intelligent creatures, if you do get one, a boar is probably your best bet as sows come into season on a very regular basis, every 3 weeks in fact and although they don't bleed like for instance dogs, they can be a nuisance nonetheless, if you get a boar then get him castrated at the earliest possible age, usually 6-8 weeks of age and this will lessen any unwanted aroma's.
Good luck if you get 1, I love pigs of all types, even the enormous ones.