What an interesting topic.
I myself work in retail while attending uni so I know a lot about the ins and outs. Our laws are similar to whats described above, but we usually honour mistakes out of good will, as someone mentioned above. Another policy we have is where if the item scans at a higher price than is on the shelf, the customer recieves that item for free, or if they have multiple items, the first free and the rest at the lower price. I frequently work at the customer service counter dealing with refunds etc, and therefore I have to deal with scammers all the time trying to twist the policies to their advantage. Unfortunately for them, I know my #### so no one gets to pull fast ones on me....I have plenty of examples if anyone wants to hear them!
I can tell which of you have never worked for a large company - the ones of you going 'but thy make a bajillion dollars every week, and make huge profits on every item. It's just not true. I will put it in perspective with an example.
There are two major retail chains in my country, I work for one of them. MAJOR company. The kind people say are 'loaded' all the time. On a good week, my store will do about a million dollars in sales. That's just one week, of what we sold through the registers. However, last year, our store got to have a party, because for that whole YEAR, we'd finally cracked the one million profit margin. I.e., despite the sales per week, once you take out cost of items from wholesalers, wages, losses, etc, this store as a part of a major retail company, only made one million dollars profit for a whole year. Not what a lot of people would expect I'm sure.
Before my current job I also worked for a small fruit business, who unfortunately went broke because of a drought - the cost price of produce was so huge (e.g. a cabbage at the bulk market was going for $9!) that in order to keep customers my boss was selling a lot of things at cost price, because the cost was already so ridiculous. So another example that businesses do not mark up extravagantly.
Ok, Azaezl's pogo stick example. This is extremely likely that this is a case of simply getting rid of stock off the floor, so they mark it down ridiculously just to shift it. Stores frequently do this with stock they've had a long time, slightly damaged or is discontinued, etc - basically they want it gone to make room for new stock, and they don't care what they sell it at. Also, my store frequently marks down food items APPROACHING the useby date so that stuff will clear first - it's below cost, but the store would rather get a little money back on it and shift the stock rather than throw it out and get nothing. So your example doesn't really hold up.
Coming back again to losses. Stores calculate the losses through stocktake, which depending on the store is done every few months. We count the floor stock (what we have) and backorders (what we've had in the past) and compare it to the register sales - subsequently we can calculate our losses (through staff/customer theft, register operator errors etc), where the major losses are, etc.
The OP's guppies will be a part of Petsmart's losses for this period. Becasue it's pretty hard to steal a fish inconspicuously, I'd say these losses will come back on employees. I agree with the posters who say this was dishonest of the OP. I agree there's a huge difference between realising you've been incorrectly charged after you've left the store, and deliberately not saying anything when an employee makes a mistake. I try to help and be honest with employees and treat them with respect because I've been on the other side of the counter myself and I know what its like. Not to mention in the case of fish stores, I've frequently seen people bitching on this board about how hopeless and uneducated these store employees are. The OP had the perfect opportunity to provide this employee with some information about the differences between male and female guppies, yet they chose to take advantage of them instead, rather than educate.
I think that's about it from me...
P.S. Others posted while I was typing, and I agree the point of this thread is about the morality of the OP's actions, rather than the legalities. I just wanted to use my experience to clarify some points made in argument about businesses by previous posters.
BUT... I would see that as getting a bargain (all be it a crafty one), and therefore I take the moral highground (with myself, LOL).
