Geologists, do you trespass? Do you chase your outcrop over hill and dale? Sneak over a fence to collect a nice rock specimen?
I do not. I'm pretty careful about lining up my permissions and access agreements. Even when a resident tells me straight out to just let myself in and not bother them with notifications, I still send a reminder before I go, and once I'm done with my sampling, leave a business card with a note thanking them. Part of this is personality - I wouldn't want some service person to just go waltzing onto my property.
But part of my care is because I've been burned before. For example, I put in a monitoring well (a bedrock well, with a nice steel casing keyed and cemented into bedrock) and find out only afterward that the property line isn't exactly where we thought it was. Or the time that, due to an unfortunate game of telephone, "I'll give permission once I visit and you show me the intended well location" became "I give you permission" and the property owner was mighty surprised to find a drill rig already in operation for their visit.
When I was an undergrad, it seemed like a lot of our field trips were awfully casual about property access. We had mapping to do, and we had no compunction about crossing property lines. Granted, going outcrop hunting doesn't have quite the same impact as poking holes in the ground with heavy equipment. But even if I'm just measuring strike and dip and I'm not actually taking anything except for information, I still get that permission. That measurement will go on a map in a report, and once it's there, it's a permanent record of where I've been. Saves awkward questions later. And also, it's simple to chat about the significance of that big wall of rock in the backyard with the homeowner and it may save you the indignity of getting physically chased out.