My personal experience with cheap sweat shorts caused me take a trip to the doctor for the rash, not cheap. I never had this problem on my DF's when I wore expensive lycra shorts with anti-bacterial chamois. My doctor counseled me against wearing cotton in that area since I am a heavy sweater. I have high deductible medical insurance so any money I saved on shorts was gone after the initial and follow-up visits. I now wear Under Armor boxer briefs and My MUSA knickers, together about $80USD. On really hot days I wear Sugoi's triathlete shorts, about $40. I haven't been back to the doctor for the rash. The doctor's visits and subsequent medication was over $300. I would have saved money if I just bought appropriate shorts in the first place.
I also once found a wasp and an earwig in my opened leg sweat shorts. Luckily no sting. Those are the dangers of SWB 'bents.