Ok so here's a rough walkthrough for the Amy Scavenger quest. ----Contains SPOILERS!-------
Item 1: Credit Card
-In the right side drawer in the desk with the PC and printer (next to Frank)
Item 2: Condom
-Complete the Maddison or Ashely quests (in Ashley's case, ask and keep the panties) to have access to a BJ. Talk to Frank about somebody having booze then run over to Maddison/Ashley, start the BJ session then wait for Frank to find you. Talk to Frank afterwards.
Item 3: Derek's shirt
-Talk to Derek, to the PC (near Frank) create the Petition, print the petition (right next to the PC) and go around to all the NPCs and have them sign it (by answering correctly to their questions)
Item 4: Panties
-Complete Ashley's quest (wash her clothes but keep the panties)
Item 5: Picture with the American Flag
-Talk to Britney. Complete Stephanie's quest to get her to dance topless. Talk to Britney again to make her go down stairs. Go to the upstairs closet (not bedroom closet) and grab the broom. Go to the living room and grab the right speaker. Go behind the pool and interact with the patch of dirt. Stick the broom in the ground then interact with the broom to put the speaker on it. Turn it on then go back to the living room and turn that speaker off. Wait for Stephanie to go to the pool and wait for Britney to follow her. Talk to her once at the pool. Go find Amy and tell her about Britney.
Item 6: Goodby Kitty underwear
-Go in the garage and search the front rack. Should be in one of the lower boxes.
Item 7: Can't remember but shouldn't be too tough since it didn't leave any lasting memory
Item 8: Skinny dipping selfy
-Talk to Britney then to Amy. Convince Amy to go in the hut tub and start a Truth or Dare session. Ask the questions related to them (not you) and once you've asked enough you'll move on to the Dares. Dare them to strip, then loose the shorts and talk to Amy. Important! At the truth or dare stage don't save between questions/dares. If you do their cloths reset and you won't be able to continue.
Quest done. Go find Amy upstairs.
Talk to Amy and depending on what you say, you'll get a Amy that walks around the house with different levels of clothes on. Thanks kinda it.
Did anyone find a different ending?