I dont beleive that you will have a problem with it preventing a fish to bite one of your other baits if that is what your asking. The real problem is that you have a bait (lure) out that will not be picked up. You would now have one extra line (that isnt working) to clear or deal with when you hook up on another bait. The other problem is that sometimes a lure that is fouled can entice a fish but when they do strike it they're not hooked. My advice is reset the bait and if you cant get it to troll right dont troll it. As for size and color it can be tricky, there are days when one color will be consistant and other days that you catch every other fish on a diferent color lure. I have a few different spreads that I like to troll, what determines which one I use is usually sea conditions. You need to experiment with different lures in different conditions and whatch how they troll. Write down what works with what conditions on your boat, also realize that what works on your friends boat in a certain sea condition might not work at all on your boat. Basically what it comes down to is you need to put your time in and figure out what will work for you and your boat. Once you figure out the best spreads for your boat you just need to concentrate on where to troll them.