If someone makes a useless suggestion and you have a valid reason why their suggestion is useless, unless they are an idiot, it shouldn't be a challenge to explain your reasoning.
Like so:
Other Person: "You should do _insert well intended suggestion_"
You: "I would but _insert valid reason suggestion isn't helpful_"
Other person: "Oh, I see. I'm sorry I couldn't help."
Et voila.
ETA:
If the above doesn't seem to be working, it may be time to look at your reasoning skills. Maybe you aren't being as objective as the Other Person and their suggestions are more valid than you think. From reading your replies to threads here, it seems that every time someone answers a question that you ask, you have another question. Every time someone makes a suggestion about a situation, you have a counter thought. It's not a bad thing, necessarily, but if you find that you're constantly playing devil's advocate or constantly pointing out what every around you missed, there may come a time when you need to examine whether it's really them or it might be you.
As I asked, please do not connect every thread together.
I am sure you argue with people in your life.
And as I said, internet forums are semi-anonymous and an approipriate venue for delving into topics.
If I ask a follow up question, people can choose to just ignore it.
Isnt it better that we all ask 1,000,000 questions and another 100 follow ups here then where we serve?
Its simply trading information. It is dangerous to discern intent from the written word.
Where I serve now, my vollie, I ask a few questions, mostly I just sit and follow along with what is happening, and my usual question is " where do want me ", and I get a bag, equip, etc as told, and if I am told to do the intervention myslef I do it, if I am told to hand the item to someone, I do that.
I must be doing at least satisfactorly as I am asked to ride in the bus as often if not more than others in the pool of newbies.
I was asked to a guy's wife's birthday, which I had to bow out of, but I made an appearance anyway to wish her a happy and drop off a small gift (one of those edible arrangement things), one my students parents has a frachise....