Easy.
Buy from a reputable source; detailed image, detailers domain, sky’s the limit (US distributor of CarPro), AMMONYC, etc. (Please please people stop buying stuff off amazon- it could be counterfeit, years old, or explode in transit because they didn’t pack it correctly)
Second, do your due diligence. Some forum posts may be years old, but they are typically written well because they actually cared back then. Read reviews on said websites above. Take YouTube with a grain of salt.
Third, sometimes you have waste money. If it looks like an interesting product and it’s not outrageously expensive.. what’s the worst that could happen? If you’re super peeved about it, use it on your toilet or something.
It’s also super product specific. CarPro makes some stuff with.. mixed reviews. Chemical Guys does have one or two things that do, in fact work, and quite well.
The truth is, what works for you or some guy on autopia or on r/autodetailing may not work for you. Environmental conditions, paint conditions, dirt / contaminant levels or type, all contribute to the level of gloss and cleanliness possible. Volume detailers have WAY different requirements versus a bespoke detailer. If I was running a volume shop I’d just run all Meguiars all day. But personally I stick to “boutique” products because I find they do offer slightly more refinement.
Ceramic coatings do work quite well, they just take some serious prep time and you have to be willing to get everything squared away for the best possible bond. People don’t put in the work to actually maintain them, which leads to poor performance.
Wax over a sealant works in certain situations. Collinite 845 and Jescar Powerlock is a known combination that works well (but does “sweat” and is tricky sometimes). AmmoNYCs Reflex / Skin / Creme scheme is engineered to work together. Alas two unknown sealants and waxes may end up reacting poorly or the solvent of the wax may simply eat away the sealant. Sometimes it’s best to stick with one manufacturer for your “protection”, like Cquartz and Reload, or Crystal Serum Light and EXO.
On that note, personally I think “toppers” are bullshit too. Cquartz does / did need periodic Reload coverage, but you don’t need to slather your coated car with something. It may even kill the coating faster or “clog” it preventing peak performance. Modern microfibers taken care of correctly will not scratch your paint. If you’re like me and enjoy the feeling of waxing a car, just use wax.
Same goes with coating everything. Your leather doesn’t need a coating. Your floor mats don’t need a coating. Your carpet does not need a coating! (Your wheels do need a coating, it makes life so much easier.)