I sell in a niche area of glass which once had its own sub-cat. within the main category of "Pottery, Porcelain & Glass > Date Lined Glass - 1919 - 1939 Art Deco." which if searched for returned about 10K results. It had very little in the way of 'tat' or irrelevant listings. It was easily searched for, being a named sub-cat. and it was a lively market in which I got regular sales simply because I changed what I listed regularly.
Ebay effectively sabotaged that market by getting rid of the sub-cat. and making what was a main category (PP&G) into a sub-cat. within the new giant category of "Home Decor & DIY > Pottery Porcelain & Glass > Decorative Tableware & Cookware with specific items such as > vases / > bowls etc.
They removed any mention of the date-line, the style (Art Deco) and submerged the 10K items under a mountain of "Art Deco Style" modern tat and any other irrelevant item that a seller decided to label as "Art Deco". Such as a few hundred genuine 1930s candlesticks in with thousands of modern "Tea Lights and candle-holders", many not even made of glass but made by the million in China. Buyers then have to try to find them by using IS, if they can.
I would agree that where comparable items can be seen together they will find there own price level, but not when they're scattered, one or two to a page, among a sea of dross.
Ebay also decides that slower selling items are "Stale", just because the are slow to sell, something that is inevitable when selling in a niche -- the smaller the niche the slower the sales. But that doesn't mean they are over-priced or unsaleable -- just that they won't sell quickly. It's only ebay that defines it as stale and down-grades their visibility making sales even slower.
That policy alone has made selling many collectables un-viable on ebay. Last year I would have listed about 50 different items, faffed about re-listing as "Sell Similar" to re-fresh them at intervals and managed to sell 4 items.
On ebid, where RUS means "Run Until Sold" (without any of the faffing around), the last item I sold was listed in 2021. I also sold 27 other items in 2024, all of them listed or years and all sold to buyers happy to have found them and paid me the full asking price.
I think that demonstrates that it isn't always the second-hand stuff that clogs the search results, it's equally modern stuff that clogs the the results in most collectables categories and prevents items "finding their price level". Ebay has forced them into competing for visibility in a modern item mass market and lost tens of thousands of sales by doing so.
One reason private sellers list continuously is because ebay forces them to by controlling and down-grading visibility if they don't. One reason I put stuff on the other site is it saves me all the faffing required by ebay to stand any chance of selling anything (and that's without even beginning to get onto the requirement to Sponsor my listings to get a sale).
The basic problem is not always private sellers being unrealistic in their pricing, Kath's old suit and my old vases will sell if they are given a decent change but ebay manipulates the search, denying slower selling items visibility and submerging them in a sea of modern tat, not because they won't sell, but because they don't sell quick enough to suit ebay.
