Apollo 12 was able to land in very close proximity to a Surveyor probe because its location could be determined from images originating from Lunar Orbiter probes. I believe its shadowed image was also discernable in the LO pics. Other LO images showed long shadows from boulders that had rolled down crater walls. So, yeah, it is possible to see them unmanned landers, and it has been done.
Apollo 12 was able to land in very close proximity to a Surveyor probe because its location could be determined from images originating from Lunar Orbiter probes. I believe its shadowed image was also discernable in the LO pics. Other LO images showed long shadows from boulders that had rolled down crater walls. So, yeah, it is possible to see them unmanned landers, and it has been done.