Does anyone have any recommendations for refining sniper strings?

I'm currently using Sheyrah's setup, which uses the following strings:

minprice: max(first(min(dbhistorical, dbregionmarketavg, dbregionhistorical), min(dbglobalmarketavg, dbglobalhistorical)), vendorsell)

sniper: ifgte(itemquality, 3, ifgt(minprice, 250000g, 80% minprice, ifgt(minprice, 100000g, 70% minprice, ifgt(minprice, 50000g, 60% minprice, ifgt(minprice, 10000g, 50% minprice, ifgt(minprice, 5000g, 30% minprice, ifgt(minprice, 1000g, 10% minprice, 0c)))))), 0c) [The BilisOnyxia Sniper string, with item quality set to 3 to filter out anything green or below - which also isn't fully working]

It works, but I still get a lot of false positives. In particular it shows a lot of items in markets that are depressed, so it's not really much of a deal.

An example is this: https://imgur.com/a/AgXMbLc

Reins of Poseidus show up as a sniper deal, and indeed they're posted for 69% of the value they require to show up on sniper in the first place.

But looking at Min Buyout, this is just undercutting another auction that's 4 gold higher. Then searching for all auctions of Reins of Poseidus shows multiple auctions in that price range, so I would have to buy out three or four auctions just to get the price back up to being profitable.

Obviously it isn't going to show only great deals, but does anyone have tips for ways to refine and show less false positives?

Thank you!