Noise at idle, if clutch, then away

Hello, I would like to buy a Toyota Avensis 2,2D-Cat with 177hp. When the engine is idle, there’s something going on in the engine room. Sounds as if a plastic flag is clapping on a wheel. When I kick the clutch, it’s going to be less/goes away (I couldn’t hear that much anymore because the salesman had the door open). He said that this was the backlog and only a beauty defect, which lasts forever. During the test drive I saw blue smoke in the rearview mirror. The car has a very good equipment, 100,000 km, year 2005 and is supposed to cost just under 11,000 euros. Now I really don’t know, you can buy it or rather get your finger off. Thank you The New thowalu