Briel:
To me, it's an invitation to look deeper at those games to see why they were deleted (if there are clues in the OOC). Lots of deleted games with small post counts is a flag to me that warrants investigation. Sometimes the GM has just been cursed with bad players. Sometimes, the GM turns out to be unreliable for whatever reason(s). Sometimes I see a poor GM who drives away players. Regardless, what I find in some of those deleted games definitely influences my decision to submit a RTJ.
I'm with Briel 100%. While there are a variety of reason why a given game may be deleted, it's still nice as a data point looked at in a broader context.
For example, while it's true that people can reuse games so as to hide their deleted status, all that means is that deleted games cannot be accurately used for relative means of comparison. They
can however still be used to communicate potentially useful information about an individual GM who has a lot of deleted games showing.
Look into the games themselves. How long did the game run? How many players did it have? How many posts did it have? You can't know for sure, but can usually make a pretty good educated guess as to the reason for the game's demise.
That educated guess taken into context with other factors (their active games, their inactive games, the style of RTJ, the content of their GM posts, etc.) may help you come to a conclusion as to whether or not they're a good fit.
People on RPOL very frequently complain about GMs bailing on games, but frequently don't spend the small amount of time it would take to see if a GM had a track record on hand that could help them suss out that information beforehand.