Hi Rita, I was the one who initially bandied about those words, terrible, dangerous, irresponsible, which I stand by and I will explain why. You say that you assume everything else was perfect, but you did not make this clear, and anyway this is just not something that you can reasonably assume, ever, because even if you were going to trip-sit the poster yourself, for someone who has never done psychedelics before, there are hidden dangers that you cannot reasonably plan for or predict... in that specific individual's brain chemistry, any underlying psychiatric issues or any genetic predisposition to such. Because of these things, even if the planning and the setting is absolutely perfect, it is STILL possible for someone to have a Very Bad Time on even a particularly low dose of any psychedelic.
Even if the planning is perfect, it is still NOT GUARANTEED that they will have a good time, or even a bad time that doesn't leave them with lasting psychological scars. For these reasons, I would say that even if you were trip sitting someone yourself it is still irresponsible and dangerous to give them 550mcg of LSD for their first time, and I'm really baffled that you would even try to argue this point... Added to the fact that you obviously are not trip sitting the person yourself, they are a total stranger over the internet, and despite what you have said since you offered no other advice except to take 5 hits... well, I think "terrible" is quite an apt description for that advice.
You say you take acid seriously, and yet you speak of it like the dangers of bad trips are overblown and everyone should just chill out and take massive doses without crying about it... I would venture to suggest that this is likely something to do with your personal beliefs that LSD is some kind of god-given gift to man rather than a fortuitously synthesised and unusual chemical with some strange effects on the human brain. Everyone is entitled to their own beliefs of course and there is no reason LSD can't be both, BUT it is a mistake to be so flippant about the dangers because as I've already stated bad reactions DO happen that sometimes just could not have been predicted.
To be honest I find it offensive myself that you would even try to suggest that some caution when approaching powerful mind-altering drugs is in any way analogous to the sustained and monumentally harmful misinformation campaigns waged on these substances by government agencies in the name of prohibition... I would say that in fact your apparent unwillingness to accept that there are quite real dangers when it comes to high dose psychedelics, quite apart from any actual chemical toxicity (or "poisonous" tendencies, in your words), is just as bad as the prohibitionist myths which say the opposite. Your current position does nothing good for the psychedelic or drug-taking community at large, and I hope that you can see the reason in what I am saying and moderate any future advice regarding dosing for psychedelic-naive individuals accordingly.