At a glance it seems the most frustrating scenario (and therefore the one most often complained about) is dealing with people who say "My friend did x, and they got better!" or "Have you tried y, I'm sure if you did that you'd be fine!"
(Often tempting, rarely constructive.)
Now, having been diagnosed for coming up a year and ill for over two I am completely aware of why advice you did not request can be immensely irritating. I also understand why constantly replying "I've tried that - it didn't work for me" only to be argued with makes the blood boil after a while. I don't want to sound like I'm coming from a place where I think everyone's too sensitive and that there's no real problem.
I honestly think the issue is in how the advice is given. On the face of things there's nothing wrong with someone hearing about something or seeing something on the internet, thinking of you and making a mental note to pass it on in case it is useful. I actually think that's a positive thing and it's nice to be thought of. The suggestion may not be of any advantage but it's the thought that counts.
Something I've been guilty of saying in the past (with no small amount of exasperation!) is "Don't they think I won't have tried it already?". Over time though it's occurred to me that it's an illogical assumption built upon the very shaky foundation of my patience wearing thin and nothing more sturdy.
Unless you are both omniscient and omnipresent then it is simply impossible for you to have either had sight of all the information housed at the myriad of sources available to us, or to have tried absolutely everything there is to try. If you somehow have managed that then it suggests to me you're probably some sort of god, in which case may I please respectfully request you stop slacking and get back to work on a cure?
At the heart of this problem I believe is the way in which the information is imparted - not what you say, but how.
To give this a more general context, one of my pet hates in life is people who are know-it-alls. The problem isn't that they are knowledgeable people, I like intelligent company and thoroughly enjoy learning about topics which are new to me from such individuals, but it's the attitude that goes with it. You can be knowledgeable without being clever at anyone else's expense, and you can offer the knowledge when approached for it, instead of being the sort of contemptible fool one can find riveted to a Google search so that they can be the first to come up with a word-for-word copied answer and "look clever".
I see this in much the same way - you can offer these pieces of information you've discovered in a sensitive and constructive fashion, and not by demanding the person on the receiving end accepts your miracle cure from the off. For example, when the research I made mention of in Elementary, my dear Watson was first widely released, I think six different people sent it on to me. The fact I'd already seen it the latter five times really didn't matter, I was just grateful for the thought. Nobody said "See, there's an answer so you won't be ill anymore!" or anything equally ridiculous.
The two seemingly unrelated scenarios share a common undoing - know-it-alls and those pedalling their unasked for "Just do this and you'll be fine!" cures don't impress anyone with half a brain.
It did occur to me my take on this is probably coloured by my relative lack of negative experiences in this regard. Few people have ever been rude to me in making suggestions, and I feel it's better to encourage people to do so than to seek to put them off because you've "already tried that" and so push them away and discourage them from trying again. You never know what they may find which you could overlook.
In closing if you do ever want to suggest something to me, speaking personally I'll always welcome it - I'm pretty up to speed but nobody's perfect, and there are plenty of old wives remedies and odd new-fangled options which aren't so widely recognised. More widely speaking it is probably wise to bear in mind the likelihood the ill person has heard it before or tried it, and try to avoid presenting anything as if it's a miracle cure. That is downright irritating I'm afraid. As with all other things in life, manners and attitude count for quite a bit indeed.
(Flavour-changing medicine. If I had that, I honestly wouldn't give a damn if it worked!
Image courtesy of cosmicplay.net)
Think about that, and the medicine may well go down in a most delightful way.
In case you don't know about the blog's Facebook page (here), then you may not have seen my news! I'm one of the group of new admins for the Chronic Illness Cat Facebook page. It's been in The Warrens tab for quite some time now and I'm delighted to be involved more closely with such a great community page. I strongly recommend it both for discussion and a healthy dose of dry humour.
Come and join the sick kitties laughing!
Wishing you all many spoons xxx