I have been a collector for the past 60 years. Inherited 2 collections.
If I sell them individually they will be in very good condition.
If I sell the entire collection, it will be as a mix nag. majority will be in very good condition.
I am not a stamp dealer.
I have never sold a stamp.
Between years 1980 and 1990 I spent $20,000 (Can. $s ) buying stamps and first day covers.