I'm glad someone has already brought up the terminology issue.

I think it aids everyone's understanding if they use the right terms.

Just to re-iterate what Bax said............

A Deep-stall is unrecoverable. It's unrecoverable because elevator authority is lost.

What you guys are describing are just stalls, unless they genuinely are unrecoverable. It is quite conceivable to deep stall a model and get away with it, as a great number of models are drastically overpowered and easily have the power to impart forward airspeed again.

Please note that if the glider seen was genuinely deep stalled, then the landing really would have been something to behold, because it's not possible to flare out and check the rate of decent, because it is, of course, stalled.