After ordering RCs for years, some notes on both good and bad aspects:
BAD - been burned twice. $$$ was the most. It hurt. Very angry, but nothing could be done. Send money to bloody poland or china with no guarantee of anything, and you either get back some shit which is A) poor quality, B) toxic and dangerous shit, C) less than you paid for, OR you don't get anything and they won't re-send. What are you gonna do?! What recourse do you have?!
BAD - variable quality of substances. MXE is a good example for this issue. Ordered from different places and got all kinds of shit which behaved in different ways. Some batches three times stronger than previous ones. Woops. Some clearly NOT MXE at all.... some weird, dirty, unenjoyable, heavy, confusing, dissociative thing, which left one with a sick feeling as having ingested something toxic (which is probably exactly what hapened).
BAD - Mis-labelling (as mentioned above, can be fatal) or in one case, NO LABEL AT ALL. Also, a couple of times "free sample included" which I didn't ask for and is very illegal in my country. Thanks!! I would never have ordered that in a million years knowing how hot it is and how much trouble I could get for it - even a small amount. Just give me what I paid for.
GOOD - there are reputable, professional, closed (ie. invite only) vendors out. These rare few are precious: reliable, reasonable price, consistent, honorable. It takes time to find these because they operate on trust and are not simply out to make as much money as possible. I have had access to substances which are sold as medications here, which I would never have been able to afford, or would have been denied a script from a doctor.
All up: It's a big, big risky game ordering RCs online. I doubt that many people who order RCs online then go on to actually have their stuff independently analysed, verified, etc. So, really, you're placing a lot of trust in people you don't know and most of whom are operating for fast profit. However, all things considered, I have had worse experiences buying drugs on the street than I have buying RCs online.
Mind you, I've been buying and using for many years now, and have seen the ins and outs of various scenes. Whether it's online, or in real life, it's the same old story: it comes down to who you know and how much you trust them.