for a 16pt 4team teaser:

if there is a game with a total (original) of 30-38, and the spread (original) of that game is less than a touchdown (and greater than 2.5), the underdog will COVER their spread after the teaser adjusts it. (FOR THE VERY MOST PART)

For example, week 3:

tampa+16 (original +3)
carolina+16.5 (original +3.5)

i guess it really depends on the defenses. the total is low for a reason.