Hank-
Yeah, I have the same clause in my wedding agreement as well, but I figured for as much as these guys were paying me for two hours of work, I could take a little smoke. Of course, I forgot it was the last weekend before the smoking ban, and that all the smokers would be out enjoying the last smoke-filled bar-going weekend in Minnesota history.
On the uber bright side, I can be guaranteed that at least at my Minnesota video shoots, I'll never have to worry about smoking again.
Oh yeah, you reminded me that the DJ at the wedding I did would not let me tap into his audio (I think that's a first). He didn't say why or even try. He just said no. I put a mic in front of the speaker and it worked great.
I've only run into one DJ who said no to plugging in. I told him that I keep a list of cooperative vendors, and many of my brides use that list to help them decide who to hire. He eventually gave in, and yes, he's now on the list.

At a wedding a few weeks ago, we had a terrible DJ. I mean, a horrid, rotten, simply awful DJ that I not only will never recommend, but I will go out of my way to ensure that nobody I work with hires him. I mean, he was sincerely the worst DJ I have ever seen.
First off, let's talk some more about smoking. He was so hooked on his nicotine death sticks that he would literally come inside, chance the CD's, and step back out to smoke for 10 minutes or more at a time. Several times throughout the night he was out there so long that his song cue rolled back over to the first disc again. There was one moment where the same two songs repeated three times before he came back in, swapped songs, and went back out to smoke.
As dinner was getting started, he was (of course) outside smoking, and the family wanted to have a prayer and say a few words. Nobody could find him (it turns out he ran out of smokes and drove to the nearest store, about 3 miles away), and so I wound up taking charge, muting his music and turning up the levels on his wireless mics so the show could get going. Of course, because of this, my camera missed the first few moments of this important part of the night. Ugh!
When he finally did show up, it was time to play the montage video we made for the couple. Normally we have our own amp & speakers for this (I don't trust DJ's as a rule-nothing personal), but this guy was insistent that we could run the sound from our laptop into his board. Big mistake on our part. He plugged our line output into his board, into a channel that he accidentally had cranked to the maximum level. When the DVD started, the audio probably would have deafened anyone within 20 feet of the speakers. Of course, I later overheard him talking to the MOH, trying to blame us for having levels that were "way too hot". Of course, at this point, everyone was tired of this guy, so she didn't take it seriously at all.
Fast forward to the dances. We actually nail the guy down for 15 minutes to do the First dance, F/D, M/S, and wedding party dances. Actually, we didn't nail him down. More like he would go start a song, run out and suck one down, and get back barely in time for the next song. Anyway, he put the CD in for the first dance, and it wouldn't read in his CD player. Now seriously, this is one of the most important events at the reception, the first dance between husband & wife. You'd think he would have checked the CD earlier.
Fortunately, by the sheer grace of the good Lord, I happened to have that song on my laptop from another event we did, and I once again plugged in and saved the day. This time, I took control of the mixing board though. No more of his deafening booms that he'll try to pawn off on me!
At this point, the couple have been standing out on the dance floor for about 2 minutes with no music, and it's getting a little awkward. Seriously, If you haven't tested the disc yet, don't call the couple to the dance floor. But that was the thing, he was trying to "get it over with" so he could go back to playing songs while he slipped off to smoke.
Once these events were over, he said "The dance floor's open everybody, come on out!" and put on a song. That was 100% of the crowd building this guy did. After the song started going, he would slip off and smoke. For the vast majority of the evening, either nobody was dancing, or it was only people in the wedding party, trying to liven things up themselves. Many times, his two songs would wind up repeating over ant over, and a few times I got tired of hearing the same set of songs back to back, and I went up and swapped songs for him, and for the sake of the crowd.
During the dollar dances, he was pretty much forced to stay up on stage, but honestly, I wish he wouldn't have. One thing I haven't mentioned yet is that his girlfriend came to the reception as well. She wasn't quite as bad about smoking as he was, but just about. Anyway, while they're playing the dollar dance songs, this guy and his girlfriend are up on the stage where the DJ gear was set up, and essentially dirty dancing...to slow dance songs!!! It was truly disgusting in so many ways. Weddings are about love, and they were essentially participating in a lust match, right there on stage, while the crowd is trying to do dollar dances.
The crowd was insanely thin by the end of our evening, and a week later I was speaking with the bride, telling her I didn't want to charge her for the last few hours, since I really didn't get any useful footage, due to the DJ. She told me she wanted to pay me anyway, because had I not been there to do his job for him, a lot of the evening would have been a whole lot worse, not to mention the fact that we saved them on their first dance.
Seriously, up until that wedding, I didn't have a list of vendors that I recommended
not hiring. Now I do, and His service is number one on the list.