The secret to scraping off an old finish is to use sharp tools. Old paint is abrasive and will quickly dull steel scrapers. You end up doing more sharpening than scraping.
This carbide scraper with a 9/16" square blade solves this problem of clearing glue or paint from 90° corners. The blade stays sharp many times longer than steel and is reversible for a second life.
With an ugly yet comfortable handle, this scraper is incredibly good value.