If something is a trap, it's because it doesn't work. Not because someone makes it not work.
Scouting is about sending one person off alone to see what's there and report back. There are many different ways you could do this. All of them have all of the following problems:
Well, at least you're listing your definitions this round, even if they're not correct - scouting is about finding out what's ahead; the method doesn't matter. As I said, most of the time, spells generally provide enough to get by. Now, I have played in campaigns where the encounters are designed to kill parties that go in without knowing exactly what they're up against, and since magic is the largest threat, it's treated as such, and anti-divination/AMF are used extremely heavily. And in that case, you really do need a semi-dedicated scout. Unseen Seer and SCM work pretty well for those kinds of campaigns, allowing for both magic and mundane sneaking/scrying and still have use during the actual fight.
And let me be clear - in general, a dedicated mundane scout is a trap, yes, But scouting in general, not so much.
AMFs mean a high level caster who cannot cast spells. Anti divination does not block all divinations and anyone that has that can easily stop hiding. Unseen Seers are casters who have sacrificed their actual power to go off alone against fights meant for the entire party. SCMs are better but they're still not going to be able to solo everything. Even if they could, perhaps because you subscribe to the mentality of pale shadows of enemies vs super optimized builds... one person is soloing everything, everyone else is doing nothing. That's a trap for a different reason. It will cause your fellow players to smack you in the back of the head.
There are ways you can find out what's ahead. Generally that involves the divinations that even anti divination measures don't block, research, or simply being prepared for common scenarios and attack forms. If you have a Mass Resist Energy scroll it doesn't matter if the next encounter is a pyrohydra or a breath strafing dragon or a horde of Fireball casters - it will stop any one of them just as well.
Sending one guy off alone to find out is a trap. Focusing on it is more of a trap. There are just too many ways of stopping them
by accident. Without them consciously deciding to do anything about some guy sneaking up on them or to prevent that from happening.
Before making that post I looked at several dozen different stat blocks. Almost all of them had at least one method of automatically detecting them. Most of them could easily kill a Rogue or similar in a single round. Many could do so even if their role in the encounter was as mooks... for example, there were several different creatures all under level 10 that snakeman's high level Rogue could not even touch and that could easily kill him despite being so low level he wouldn't even get any experience points for defeating them if he somehow could, or alternately that gave so much experience to the enemy that there isn't even an entry showing how much they get for defeating the Rogue.
If you're getting beaten by something less than half your level and the only reason that's happening is because becoming entirely immune to you is easy it's safe to say that that is a trap.