When my wife says no.....i always make sure i ask 'why?'....do it in a semi-serious manner....find out the reasons why she does not want you to do something(dont accept "because I dont like them" as an answer...find out the details)...then depending on the reasons that she gives, you should be able to adjust your 'sales techniques' and do some explaining and possibly get a snake or just quit the attempt all together if her reason is well justified