As adjectives the difference between saggy and waggy
is that saggy is baggy or loose-fitting while waggy is having a tendency to wag.
saggy
English
Adjective
(er)
Baggy or loose-fitting.
That sinks or droops from wear or its own weight.
waggy
English
Adjective
(er)
having a tendency to wag
Synonyms
*waggily