@tstage,
Your search terms "HO Scale" is a little too broad. Try HO scale trains with no category . On the first results page you can use the filter terms just under the main search box or the ones in the Left hand column to get more specific results.
I generally have an idea of what I'm looking for, and model in N so my searches are:
N steam > locomotive, >boxcar> passenger cars... If I want a specific road name I write it out then add the short version Pennsylvania Railroad PRR > New York Central NYC... so I do not miss any titles. So you could try, "HO scale New York Central NYC passenger car".
If you want a specific type of passenger car you can add (combine, pullman, dining, baggage...) between NYC and Passenger. I leave out terms like streamlined and heavy weight because many sellers do not add those terms to titles.
Search:
(1) HO scale trains > toys and hobbies. 27,300 results, Note how many refinements under the title and down the left side of each page
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2555059.m570.l1313&_nkw=HO+scale+trains+&_sacat=2...
(2) HO scale trains no category
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=ho+scale+trains&_sacat=0&...
28,100 results, more refinements under the title and in the left column.
"THERE IS NO SUCH THING AS FOOLPROOF, BECAUSE FOOLS ARE SO DARNED INGENIOUS!" (unknown)
