I haven't encountered it much (through also largely buying new) but a few times I've had that and been confused by the seeming arbitrariness of what's highlight

I haven't encountered it much (through also largely buying new) but a few times I've had that and been confused by the seeming arbitrariness of what's highlighted. As in it didn't seem important, insightful, or the hardest/least intuitive thing on the page, just nothing. Trolled by previous owner perhaps.