I come home to a pile of debris in the front yard and an enthusiastic, "Honey, we figured out where the front porch is leaking!" Apparently they were bored when I was at a party one night, and decided to get out on the roof and do some poking around. They pulled up some cracked, bubbled tar where we suspected the leak was originating and under it found layers of rolled shingle and some very wet plywood. So rather than simply putting another coat of tar on the roof like we had planned, they decided to pull up that entire area first and "fix" it.
Rather than just buying a couple buckets of tar like we planned, we ended up using 3 buckets of tar, 58 feet of rolled tin, half of a box of roofing nails, a couple sheets of plywood, and a dozen or so tubes of caulk. Ugh! It's only temporary, but it still beats the $10,000 (no, I didn't put an extra zero on that...) it would cost to have a flat rubber roof installed.