According to the bottom of the page of every SE site:
site design / logo © 2016 Stack Exchange Inc; user contributions licensed under cc by-sa 3.0 with attribution required
Everything any user posts is cc by-sa 3.0 licensed, which following the link excludes all warranties.
No warranties are given. The license may not give you all of the permissions necessary for your intended use. For example, other rights such as publicity, privacy, or moral rights may limit how you use the material.
Added to the terms of service Aurora already cited, SE and us users seem to be very well shielded against legal liability—as long as no one can prove harmful intent1.
Handling Potentially Dangerous / Flawed Posts
With my layman legal evaluation out of the way1, I say we shouldn't start marking some posts with legal disclaimers. The reason is simple. If we start putting organized disclaimers on some posts we create the impression that everything else doesn't need the disclaimer—furthering the false assumption that everything else can be used without any own thought at all. So let's not do post notices.
As the CC license tells us, there are no warranties given and it does not even mean I can use anything mentioned in the answer. Simple example, just because an answer mentions a commercial software, I cannot use it, I still have to buy it first. Even if that answer were to give hints where I could find it.
Furthermore, which legal code would one use as basic? US, because Stack Exchange is based there? The country where the OP or the answering user comes from because they happen to know something about that legal situation? Or err on the side of caution and pick the strictest law? How to find out which one that is? Do we stop with safety? What about privacy, security, violation of radio bands, copyright, etc ... That would require full-time lawyers to assess most of the posts on the site.
Neither we as users, nor any future moderation team will be able to catch every pitfall in every post. Even worse, if a moderator decided that a safety note is not necessary, the legislation or other bases for his or her assessment could change, so a post notice for such concerns would have to be re-assessed for every post on a regular basis. No voluntary staff of moderators and user reviewer pool however big can provide a consistent tagging with post notices. So let's not start with it in the first place.
However, that does not mean that one can't as a user provide all the warnings one deems appropriate as part of the answer, question or comment. I'd even encourage everyone to rise the safety, security, privacy and whatnot concerns they have with answers because it will likely make those answers better. Better, safer content is always good for the site. If you do see answers that don't take important points into consideration comment on them, downvote or provide an answer of your own, that's everyone's prerogative as user of the site.
Stack Exchange gives us the tools to downvote, correct (by editing, commenting or posting answers), close and delete posts already. Those are the things that Stack Exchange moderation is build on. Let's use these community moderation tools rather than using post notices that future lawyer moderators can use.
Off-Topic-Ness of Legal Questions
I think in there narrow confines of IoT related legal questions we should consider having them on-topic for now. The problem with every real regulatory problem is, that there are two sides to it, a legal one and a practical one. Generally laws are fuzzy and living the law is established by court rulings and precedence. Within the IoT domain there is barely established precedence available and the project knowledge of IoT experts might be even more applicable than that of a generic legal expert.
If we as a community can't provide proper answers to those questions, we can always re-evaluate—or try winning a legal expert with IoT knowledge.
1 Not a lawyer