A lot of the Norlin era guitars are no where near crap. For example, Angus Young's first SG was a 1970 Norlin era SG. This guitar was used for all their Bon Scott-era records (70's) and the first few in the early 80's, both live and in the studio.
However, many of the Norlin era guitars were crap. Many of them were made out of far cheaper materials than their 60's brethren.