Question the second: when would you ever feel comfortable swindling someone's silver into a swindler? I would think they would have to be terminal-heavy and already have a swindler or two for it to be a good idea. Any other thoughts? You have 10 Market Squares in your deck and there are no kingdom cards at $6 and $8?
Ehh, there are many such cases where you don't have to be terminal heavy to want to give a swindler:
1. I bought out all the peddlers. You get a swindler, now how often are you really going to play it knowing you've got a, say, 1 in 4 chance of giving me a free province?
2. I've run loan and the curse pile is empty, I give you a swindler and you may give me 1 VP (curse to copper) and I may even, finally, be able to trash a junk card from my engine.
3. We both bought 3 swindlers thanks to early swindling of swindlers. This means that I can push the pile down to 9 coin/3 buys to empty it.
4. I've emptied out the only 5 coin kingdom pile in the game (minion, venture, whatever) and the game is getting close to the end; again how often do you want to give me a free-ish duchy?
5. In addition to Market Square, several reactions can make swindler a no-go. If I have a top decked watchtower every turn, you will thin my deck for me. If I always top deck Horse Traders, you will often give me 6 card hands.
6. You are playing with menege or hunting party; 2 swindlers can be much worse than leaving around a single silver/single swindler. Likewise, forcing you to spend a buy on getting a silver in a Fairgrounds engine deck can be strong.