Is a drilled and plugged tank safe?

I spotted what seemed like an excellent deal on a 55 gallon tank but it had been drilled for a sump and then the holes had been plugged with threaded acrylic plugs. Is this the usual way to deal with drilled holes in tank? Are they any less secure than tanks that have never been drilled?

 

Bumping this up for you

 

Thanks Coradee!

Just discovered that another tank I'm seriously interested in is also plugged, but the seller says it will never leak because the hole was drilled in a bulkhead. Isn't that still a hole in the tank?

 

Hopefully someone whow has dealt with plugged tanks can help.
My personal opinion is not to get it. I just don't trust something that has been altered, especially a tank. If it wasn't done professionally, or by my own hands, I'd leave it alone.
I would suggest that, you ask the seller if you can fill the tank, just to make sure. If they say no...run away as fast as you can.:

 

I wonder if he has the time for me to do that! He claims it's a 90 gallon tank but if the measurements given are correct it's actually about 77. It's a good idea though, thanks!

 

When you go to see the tank, just bring a tape measure with you to get the dimensions. Maybe when you make arraignments to see the tank, the seller can have the tank filled before you get there.