I book solo - I’ve not done the “no show” personally however on the other thread on this it appears Celebrity are now cracking down and repricing where a no show happens. It may be best to refer to the other thread which has a more substantial number of replies/experiences of this.
Personally I wouldn’t book an over inflated solo rate, but I guess I’ve been lucky so far that my solo rates are identical to double occupancy. Not exactly ideal either but at least not inflated.