gday Burgdog, welcome to THP
gather ten occasional chile sauce consumers, ask them all to take a taste and rate the heat out of ten, then work out the average score. or just guess - if you think it's super hot, make it a ten, if it's hotter than that then it's a 10+, wimpy heat with no burn at all 1. the great danger in making a 'guesstimate' rating is that if you are a season chilehead and can handle megaheat you will most likely under-rate, so when Joe Public comes along he will get his ass burned off and you have rated it an 8.
maybe instead of a numerical rating you could go with: mild, warm, hot, very hot, super hot, look the f*** out!!! just a thought.