The first thing you wanna do at an open house is note the slope of the floors. You can do that by walking around the house and getting a sense of whether you feel there's an elevation change in different rooms, the more people that do that and then compare notes the better. Some people are more sensitive to movement than others.
Another thing you wanna do is open and close all of the doors to see if they are square, or whether there are gaps on either end, and whether it sticks or not. Sometimes doors will stick because they've been over painted, but sometimes it's from movement.
Another thing to look for is signs of cracking at the corners of windows and doors, or signs of patching in those areas.
You also want to also look for baseboard gaps.
It's a good idea to bring a 6 foot level to the house, with that you can then get a sense of the floor slope over small sections and then just do that over various longer sections.
You also want to be looking to see if the walls look square as a hole so stepping back and seeing if you can note any overall tilting of the house or openings that are no longer square.
On the outside of the house, you wanna look for signs of a large cracking of the stucco, stucco prone to cracking, regardless, but large cracks of stucco generally would indicate some degree of movement if they are angled in nature. Note, cracking of the stucco down near the ground level is generally not related to Foundation movement but it's something to still take note of.
So these are all various things to look at while you're at an open house, it's best to take a number of pictures and then put them in a folder and send those over and we can talk about those during a remote consultation.
It's important to be aware that some of these small indications are extremely common in the Bay area so don't freak out if you see some of these, we just need to dig into other factors such as our data and other reports and all the information we have.
Whenever possible, we will also try to do an on-site floor elevation survey if the seller will allow it, we can chat about the pricing for that, depends on the location, but it's much less expensive than the overall full foundation inspection.