It depends on the content and the country for me. Some shows get a higher rating just for have having good cinematography even if the acting and scriptwriting is crap. For kdramas, the baseline for something that is good is usually an 8 for mainstream dramas. Anything lower and I know they're breaking the formula in a way that most people don't appreciate and might be in bad taste. Though for me personally, a 9 or higher might make my eyes roll as they sometimes tend to use formulas made to wrench the heart that I'm just not too interested in. But their indie stuff 7.4 - 9.0 is worth risking a look at. Doesn't gaurentee anything good though haha.
For jdramas 7.4 is also my baseline of usually worth looking at. 8 or higher typically guarentees either something really well made or something that is formulaicly good (not necessarily to my taste.) In this rating range (8+), it matter more what the content is about and what my peers think of it. For jdramas, I luckily follow people whose opinions are usually worth listening to.
For xianxia/wuxia cdramas though, 7.4-8.4 is riskier. There's less of a chance that something was rated lower just because it had a unique storyline that didn't vibe with people, and more because it was just poorly made or got draggy. Though sometimes that doesn't matter to me. I'll usually risk watching a 6.0-7.9 rated cdrama if its a miniseries. They tend to be fun and off-beat in ways that are forgiveable compared to like a 40 episode series with the same rating. Cdrama ratings are mostly useless for 40+ episode dramas though because so many of them are just rated high based on whatever actor inspired the cult following behind that rating. But, if a 40+ episode cdrama is 5 years old and still rated a 9.0, that means more to me than an airing show with the same rating.
There are also certain tags I'm more invested in. For example, there are tags that if I find a drama is rated low (like 6.8-7.5) AND it has controversial comments? There's a chance I'm going to enjoy myself. And that's regardless of the country that produced it.
For me, its more important to understand how audiences in various niches rate things and what that implies instead of just going off a number. Because these numbers don't have the same value. There's like conversion rates or something depending on the fandom 😆🤣