Goodwill is a price you paid, not a thing you own.
01
Goodwill is the premium over what a company actually bought. It earns nothing on its own, it is just a record of the price paid, sitting on the balance sheet as an asset. A big goodwill line is a bet on a past acquisition, not a factory.
02
It is not amortised, only tested. So it sits at full value until the day management admits the deal underdelivered, then the shortfall hits at once. The write down is non cash. Profit can crater while cash flow does not move. Read the cash flow statement before you panic at the loss.
03
Flip it around before you buy the share. Check goodwill as a share of net worth. The larger that slice, the more of the book is a promise about deals already done, one impairment away from a markdown.
A factory shows up in what a company makes. Goodwill shows up in what it paid. One builds the next rupee. The other is a bill for the last one. Read which is which before you trust the net worth.