Alright...here's a good question: Why do fishermen(myself included) always say "Once a fish gets used to seeing a lure, they won't bite it as readily." A fish sees baitfish everyday of its life, yet it still eats them. Is it because it knows the lure isn't a baitfish...but does look like food? Then after being fooled a few times, decides to pass on it? Thoughts?
                                          

To a degree yes , they may associate color , the way it acts . Basically it is a learned response, just like a child if every time you ate a cookie it tasted good and nothing bad happens you would probably eat every cookie in sight . But now lets say you ate a green colored cookie and puked your guts out every time you did you would eventually learn that green colored cookies are bad, so you would still eat cookies just not green ones.

Makes sense what the rod tosser has said...another way to look at this is...big fish didn't get that big because they hit every lure they seen...My experience with Striped Bass fishing..those big cows are not easily fooled with lures, live or chunk bait...A cow striper..in the 40 to 50 lb range has been alive for probably 10 plus years..closer to 15...she didn't get that big going after a striper strike...or going after a bunker chunk just floating by in the current. I think we think fish are not as smart, but little do we know.

In my experience, alot of fish will avoid lures that they have been fished heavily on in the past. Example: I used to go every day out to a pond that belongs to a neighbor of mine that has MONSTER largemouth. I would always fish a new 4" Silver Rapala Original Floater. After a few weeks of pulling out 3-4 fish a day(usually only a 2-3 hour trip) on the same lure, they just quit biting. Now this wasn't a super large pond, only about 125 feet wide and 270 feet long with a few small inlets in the south side and a max depth of 7 feet, but it seemed like all the fish had just had a meeting and banned the eating of my lure. I even tried switching to a smaller and older 3" Original black top silver mid and white bottom with a little paint tarnish, and a larger 5" new Original Firetiger(which I ended up losing to really nice sized branch), but the verdict was in on using Floaters... they just wouldn't take them. So after a few days of complete rejection, I took a break for a week, came back to the pond with a Firetiger Hula Popper and after a half hour or so of slow retrieves I hooked a really nice 6 pound Largemouth. Now I don't think we have a bunch of Albert Einsteins swimming around ignoring our lures, but fish definitely AREN'T stupid.