Hosts can easily be identified with a deepening of the voice when the symbiote is in control, as well as a glow of the eyes, though the creatures are capable of suppressing these traits to prevent exposure.
Despite Goa'uld claims that "nothing of the host survives" the joining, numerous hosts have recovered their lives after the Tok'ra safely extracted the symbiote from the host's body -- among them Skaara and Vala Mal Doran.
Children of the Gods - Sha're and Skaara are taken as hosts of the Goa'uld and are initiated into Apophis family as his wife and son.
In the Line of Duty - Carter is compromised by a Goa'uld symbiote, which the team soon discovers is a Tok'ra. This marks their first contact with a symbiote that chooses to co-exist with its host.
Stargate: Continuum - On the eve of the Tok'ra's extraction of Baal's symbiote, Vala explains to SG-1 what the host goes through when he or she is under the control of a Goa'uld.