Ive never had a hosepipe or a pressure washer near any of my bikes. Bit of muc-off on the frame, wipe it all down and jobs a good un - Peatys 'link lube all weather' for the chain (love the smell of that stuff!) and I've never cleaned a bike tyre in my life 😜 Enough speed and all the crap comes...
On the odd occasion my Fuel EX 5 sees the light of day, if there is a creak, its normally the seat tube bolt. Loosen and re-torque and it solves it for me. I thought mine was somewhere around the crank as it creaked when i pedalled, but I've since put it down to more pressure on the crank...
I would reject the bike immediately. However I feel I should counter, in as much as my new Rail 7 Gen 3 arrived early Sept, done ~150 miles all over the place with zero issues 👍