I went for a 28 mile test ride in a boat I just bought. Later when I was home ant looked in the engine compartment, it was all dusty and a mud dauber nest was on the cowling floor, it fell from the air intake. I took off the air breather cover one a fine film of dust was stuck to the inside cover. How long can I expect till the engine blows up?...
That scenario would indicate that the PO did little maintenance. Thus, you just might be on borrowed time.
Usually, when buying a second hand boat, the first thing to do is check the fluids, wheel bearings, etc, etc, before ever splashing it. That would require removing the cowl. Thus, any mud daubers should have been found right away.
The best suggestion is to do the "Preventative Maintainance" now and maybe you'll be OK.
Now here's the "Rest Of The Story" that I simply have to share.
When my oldest son was heading off to College I bought him a second hand car. Not wantijg to trust some idiot off CL, we bought it from a dealer. Paid more for sure, but it came with a 180 point checkup.
When we got it home, being the SOB that I am, I checked it out as well. In the air cleaner there was a mouse nest and several pounds of bird seed. I cleaned it, got a new air filter and vacuumed out the carb. It ran OK and I was good to go. My motto is never trust anyone.
Anywhoot, I called the Manager at the dealer and told him the story and said I would never deal there again. Two days later a check for $300 came in the mail.
Moral of the story, do everything yourself...