OK
timeshare hucksters....just say you already own one and keep walking...soon they will know who you are and back off..works great...
Vendors ...personally they do not bother me , I am always polite and say No Gracias and after a few days they recognize me and basically leave me alone ...for the money these people make ( very little) I for one admire them for standing out in the hot sun all day .
If these things really bother you that much then it might be time for you to rethink your vacation plans , after 4 times in PVR personally I find it part of its charm , nothing like a good haggle with a vendor for some t shirts ....
Good Luck