When I get an odd, not previously experienced, taste in a blend I usually put to the combustion of some foreign material that sneaked into the blend somewhere along the production line. Although, I have sometimes experienced odd flavors after a burrito from a street vendor. And, I don't do pipes for a couple of hours after a visit to the dentist. He really puts some odd stuff in my mouth, takes a couple of hours for the taste buds to settle down.
If you really want to experience a change in a favorite blend, brush your teeth, scrape your tongue, rinse with a mouth wash, follow that with a second rinse of cold, clean water, . . . then touch off a bowl. Let the smoke linger in your mouth, roll it around with the tongue and then slowly expel through the nose.
Anyone seriously testing a new blend should cleanse the palate as much as is possible before the first taste. I'm not that picky but, when I read a review I always wonder how well the writer cleaned his palate before tasting.