I’m a big fan of studying the oxidation curve, although there are a substantial number of WBers who think it’s a complete waste of time.
I’d also study the cork - keep pushing it in & pulling it back out as long as you’re studying the wine - see whether it’s a nice tight fit [or whether the cork slides in just a little too easily] - and also watch how quickly the cork crumbles and falls apart on you.
For [ostensibly] dry whites, if they show any residual sugar after the initial spoofulation wears off, then they’re immediately disqualified.
And these days, most reds I encounter just don’t seem to be built for the long haul - they’ve got way too much residual sugar and only the tiniest fraction of the tannin backbone they ought to have. [For Cabernet, I’d be steering clear of sweet purple/black fruit, and keying in on wines with a strong green streak & loamy brown synesthesia & enough tannins to pucker up your mouth as though you’d been sucking on a lemon.]
Also, be sure to do your sampling at dinner time, so you’ll know with certainty whether or not you’re tasting an excellent food wine.
Beyond, that, just trust your own judgement & instincts & preferences: If you study a table wine for an extended period of time, and decide that it tastes great to you [and matches really well with the food you eat at home], then to heck with what anybody else thinks of it.
PS: We usually try to push the sampling of table wine candidates out towards a full week [we put them back in the kitchen refrigerator overnight, down around 38F], and anything which starts smelling skanky in under a week is simply not going to make the cut.
For what I consider to be cellarable table wines, skanky better not be rearing its ugly head until out towards 10-day or 2-week mark.
PPS: You probably don’t get heat damaged wine up in Canada, but any young recently released wine, which seems tired or limp or suffering from the blues, is also gonna be jettisoned - I don’t care how big of a score the critics gave it - a young, recently released wine needs to have plenty of verve & tenacity & a relentlessly positive upbeat attitude about it.