generally speaking, when you bet KK on an ace high flop, a better hand will never fold and a worse hand will never call. small pocket pairs will generally want to check it all the way down, and you can always call strange looking bets on the river that could be bluffs:

***** Hand History for Game 2266674441 *****
$100 NL Hold'em - Sunday, June 26, 14:50:52 EDT 2005
Table Table 37123 (Real Money)
Seat 2 is the button
Total number of players : 4
Seat 4: GKallai ( $176 )
Seat 2: gabefish ( $123.4 )
Seat 3: kingdeez ( $100 )
Seat 10: yumyum71 ( $25 )
GKallai posts small blind [$0.5].
yumyum71 posts big blind [$1].
** Dealing down cards **
Dealt to gabefish [ Kd Ks ]
gabefish raises [$4].
GKallai folds.
yumyum71 calls [$3].
** Dealing Flop ** [ 5s, Ah, Td ]
yumyum71 checks.
gabefish checks.
** Dealing Turn ** [ 4s ]
yumyum71 checks.
gabefish checks.
** Dealing River ** [ 6c ]
SpeeedRacer5 has joined the table.
sillycbr has joined the table.
yumyum71 bets [$3].
gabefish calls [$3].
yumyum71 shows [ Qc, Jc ] high card ace.