ITC eligibility

It is not inevitable that from which goods are received. if condition u/s 16(2) are satisfied than you can eligible to claim ITC. Conditions are as follow.

1) Goods or Services has been received
2) Invoice or other evidence in possession
3) return has been furnished by Supplier
4) Payment of tax in respect to that supply has been made to Government

Even if I don't treat all the purchases made by me as purchases and in my books I show it as samples. Even then is ITC eligible to be claimed

No...

If you treat the goods as Samples in your Books of Accounts, then you are not eligible to claim ITC, since it is specifically BLOCKED under Section 17(5) clause (h) of the CGST Act 2017.

As per section 17(5)(h) free samples are covered under blocked credit. I don't give it as a free sample I get a consideration from the purchaser.

ITC on samples = not allowed 

Only for accounting purpose I am showing it as samples but actually I am purchasing from Amway and selling it to someone else

How you account only is the conclusive matter. Other things are irrelevant

Thank you everyone for the replies