If it's marked on a map I consider it a bad spot. I just browse terrain maps for nice looking locations and then hike there to see what it's like in person. If there are signs of other people having stayed there in the recent months then I go somewhere else.

Admittedly I have the luxury of free to roam laws so I can camp quite literally where ever I want.

Site Seeker or the ANWB app. ADAC is not that good.

ReserveAmerica and Recreation.gov for govt campsites. iOverlander is a great community driven mapping software for all things vanlife/rv, but has a yearly subscription. I believe they still have a free ad supported version, but when they first switched to that model the ads were cancer. I use it enough that the $70/yr (last re-up, may have changed) is worth it. Other sites exist that are similar. Also, just figuring out where blm land and natl forest land are and either talking to rangers for that district is a good place to start.

The state and national parks have the best camping imo if you’re interested in sightseeing/hiking and having a campfire. I don’t consider third party campgrounds unless a state or national park (or BLM land) isn’t around or they’re fully booked. Picking which tent site within the campground is best is a bit harder sight unseen— usually they provide an overview of the campground online with the sites marked so you can make some best guesses based on proximity to the bathroom, site isolation, etc. Check for reviews of the bathrooms (a lot require quarters to operate the shower).

If Fall Creek Falls is anywhere in your neck of the woods I highly recommend it! The south has some of the best waterfall hikes.

I often use national park websites if that is your destination. They have MVUM (motor vehicle use maps) that can be handy. These often list places where dispersed camping is allowed.

I’ll add that I’d love an app that can specifically filter for campsites that aren’t for rvs.

Finding sites that prohibit rvs kinda depends on the website you're reserving your site with. You're basically looking for tent only with vehicle access.

You can try going to an outdoor store and chatting with the employees for suggestions