Um, where did you get that?
Demonic possession and speaking in tongues are two different things. Not even close. Demonic possession is being taken over by a malevolent spirit entity. Speaking in tongues is a state of spiritual ecstasy in which you can purportedly speak a divine language; it's direct communion with God, uninterrupted by our mortal state.
Likewise, you don't glow if you speak tongues, or exude smoke if you're possessed. Somebody's been watching too many movies, or something. I have no clue where you got that from.
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)