Reluctantly elected as president, a lazy teenager struggles to run the model train club, but soon discovers opportunities to expand his earnings and popularity through increasingly unscrupulous business practices.

Hello, you could structure the logline a little better and shorter,
something like:

“When a lazy teenager is elected as president of a model train club, he discovers opportunities to expand his earnings through increasingly unscrupulous business practices”.
This could work as a TV guide synopsis and the movie could be funny.

Besides, as a logline, the problem is that the conflict and the goal are not clear. You have an incident (the election as president of the club), but then your character seems to have no obstacles anymore.

Try to read this document I found on the internet (very useful): http://www.twoadverbs.com/logline.pdf
The commentary about the “dr. P” logline applies to you logline too : “a logline should depict the PROBLEM the character must solve”.

I think you should focus on the “unscrupulous business practices”: that is the key to generate conflict. Give us a clue about what kind of practices cause him problems instead of telling us that that such practices help him to increase his popularity and earnings. What happens when he go deep into “unscrupulous practices”?

I hope that helps.