This is a relevant question to ask & have answered. It is subjective too. First impression is no myth. That is where red flags may appear which stops the whole process. Yes, to not only looking with an intent, but also asking is there anything else I should know? Let's not waste time

😂 No attics or crawlspaces for this agent. This body is built for comfort not speed. But, as a tradesmen of 40 years, I do kick the tires for my clients, they know about the warts and all before they write. But due diligence periods in our contracts are for just this scenario. No house, not even new construction is without it's flaws.

Certainly had Buyers look in the attic from the ladder, check the electric panel, turn on or off water spigots, some Buyers do all sorts of items before writing an offer. Usually on the second look through the home. Again, before the offer. Some want the Sellers Disclosure, some attend the Inspection, some don't and rely only on the Inspection report. Some skip the Inspection totally or even do it themselves during the contractual.inspection time period.

Inspecting the under the house space and the attic crawl space is out of the level of my expertise. That is why professionals are hired to perform those tasks.

I've never had a buyer even think about going into the attic and I suspect most sellers would not be comfortable with a random person going up there when it is easy to step in the wrong place and step/fall through the roof.  It is not something I would allow or encourage as my insurance would not cover it the damage to the house or the person.

Anything that is viewable from ground level is looked at.  The underside of the roof can usually be seen in the garage, which gives a ready idea of roof leaks.  That is something that my buyers and I look at and if I notice something, I point it out and recommend making note of it for the inspector if they decide to write on the home.

They look at the inspection report from the inspector they hired, ask questions, and gain additional information in order to make informed decisions and get further inspections if recommended. 

Not as thorough as a home inspector would but yes

Depends on the ease of access/potential for damage or injury. Have I gotten into a crawlspace or attic? Yeah. BUT I'd rather the INSPECTOR be hired depending on THEIR willingness to be thorough and if something looks glaringly off, then have it checked out prior to offer. As a listing agent, I would have already done so and made a disclosure and investigated costs, how serious etc for buyer/buyer's agent and then they can check it on their end too. 

I have had sellers promote attic space, but never had a buyer ask for access before the property is under contract. That which is visually obvious should be pointed out but the rest is up to the home inspector. 

Fred, great question and the answer is that it all depends.  I am not an inspector but I have been around the block once or twice.  The experiences i have had,  aid me in determining what questions need to be asked and answered.  

The home inspection is necessary to get an expert set of eye's after we are under contract.  Then the second round of negotiation begins.  

If there's a basement, my buyers and I would definitely check it out during a showing. The attic only if it was easily accessible and/or had been converted to living space of some sort. No if it's a crawlspace or had no floor/etc. That gets covered in the inspection which (here in MT) happens after the property is under contract.

In HI it's customary to make the offer contingent upon an inspection.  Because inspections cost money, it's kind of crazy to do it before getting an accepted offer.

Far too many buyers, and their agents, look at the inspection as an opportunity to renegotiate the offer.

We advise our sellers to have an inspection done in advance, and shared with potential buyers, so that they have no opportunity to renegotiate things later on.

Not a freaking chance am I going to climb up into the attic, on the roof or the crawl space etc.  That is our inspectors job and they are the experts, not me.  Do I know a lot, of course, but the final word comes from the expert.

Sometimes, but not often do they go into the attic or crawl space and never do they take the cover off the electrical panel box and see if breakers are double tapped.  

We usually cannot go into the attic, as most of our homes to not have stairs, would require a ladder.  I don't carry one in my carry for showings.   But, yes, view as much as we can while touring the home.

Yes, no and no. We rely on the sellers to disclose latent defects and the information provided in the seller's disclosure. Most buyers want a second showing before writing and that is when they take a closer look for visible defects, others rely on the inspector's findings.

We look at all of the easily accesible areas of the house.  We look at anything the clients wishes to see provided the house isn't disturbed.  Deeper investigation is reserved for the Home Inspector at the Inspection.