Touch wood ... lucky so far, only a couple of minor concerns, no lost parcels, no disputes, no PayPal claims.
One neg feedback left in error (iPhone problem) but quickly revised to positive. One returned item on the website.
eBay Best Match has little effect because we sell products that very few, if any, other sellers are selling.
Of course we've made our share of mistakes - mainly with underestimating postage costs - but we're getting there.
Having said that, selling on eBay, even as a small 'part-time' seller, can be stressful and we're looking forward to the holidays and no eBaying.