I think "crappy" implies an older, maybe even pre-web 2.0 design. This suggests the site has already been around for a long time, specifically before all the surveillance capitalism and general enshittification trends started. If they didn't update their design since then, that would give some hope that the site still runs more or less unchanged since back then.
This is how I'd explain the impression of trustworthiness. But of course this is only an impression and doesn't tell you anything about how the site actually operates.