Question about AdSense reach

How can I determine reach or traffic for advertiser

[farmboy]

Here's a question I don't recall being discussed here so here goes.

A new area business is of interest to me. I don't have any ownership or connection but their success can directly have connection to my success.

I use Chrome and am still accessing the site by directly typing in the domain.

Just in the past few days I have noticed when I enter the domain, the first result has the little AD colored square.

I assume this means they are now purchasing ads from Google - (AdSense?).

Is there any way I can determine how much traffic they are receiving?

Thanks,
FarmBoy

[farmboy]

I'll add more detail to my own question with this hypothetical.

Suppose I manufacture seat cushions.

A local furniture store is one of my best customers. With about 1 in 3 chairs the furniture store sells, the customer buys a seat cushion. The furniture store buys those seat cushions from me.

I'm curious about the amount of traffic the furniture store receives from their online advertising.

Is it posssible to obtain this information?

Thanks,
FarmBoy