It's the context of the music that determines the most appropriate name of the chord. Compare C7b5 (C E Gb Bb) with C7#11 with a missing 5th (C E (G) Bb F#). In the first case, C-Gb is a tritone interval. If it resolves in the music in the standard way by going to Db-F) then the Gb really is a Gb (falling to F) and not an F#, and the chord is best called a 7b5. If in a 7#11 that same note has a rising, leading note quality rising to G in the next chord, then it really is an F#, not a Gb. If the music proceeds to the next chord in a non-standard way, or nonfunctional way then choosing the most logical name requires other factors to be taken into the account such as the key of the music and the neighboring chords, etc.