All true, Mike, however, the title is not editable after a shorter period of time than the text of a post. I think the values are 12 hours for titles and 4 days for post text.
My suggestion is to not depend on the title to convey any variable information that should be in the thread. In other words, don't put a price in the title, don't say whether it is sold or not, etc. If things change, make a new post. Yes, it is a little less convenient for those interested in the items, but it eliminates editing problems, and the inevitable confusion, even when the thread goes beyond the 4 day limit.
If a short description in the title piques someone's interest, they will open the thread. Even if the title said "sold", they will open the thread - it's human nature.