There are several ways to steal from a Kecleon Market. I'll start with the hardest way and most simple way. Take any kind of item(s), step outside of the Market mat, and have insufficient funds or refuse to pay. The Kecleon will attack, as will other Kecleon that come by on the same floor. You'll probably die unless you're Level 100. However, this is the only way to recruit Kecleon, if you beat him/her. Another one is get all items on mat, then eat a Pure Seed. Go upstairs. WARNING: Your teammates will be left behind of course, so you may want them to stay back from the Kecleon before using Pure Seed. You can use an Escape Orb ONLY ON THE NEXT FLOOR if you came just for items. If you use an Escape Orb as soon as you pick up the items, you'll escape, but lose the stolen items. Another way is after picking up items, eat Vanish Seed and go to stairs. Only recommended if location of stairs is already known. WARNING: If you go up stairs BEFORE invisibilty wears off, you lose stolen items. The easiest way is to go near the stairs and use a Trawl Orb. All unclaimed will surround you, so it is recommended to pick up all items other than Market items. Hope I helped!