When last checked, ZERO websites that offered Business For Sale Listings were Responsive to Mobile/Tablets and the varied devices between.
In fact, a couple had a 'Mobile Version' but Mobile Version and Mobile Responsive are different things.  A year ago, mobile devices were somewhat standard, but began to grow very different.  How many different sizes of phones, tables, even pc's and laptops are there now?

To test one.... grab the edge of your browser and reduce the width.
You will see the web page reorganize to adapt as the screen size reduces in width, or it will not reorganize and reduce, requiring you to scroll to the right to see the rest of the page.

The following info graphic speaks volumes!
It was prepared in the fall of the year, but the message is still important!

By the way, if you own a business or bought a business, is your website responsive?
If not, call BizLocal! 1-800-785-2925