Worth noting that San Marzano is an Italian DOC, distinct from the US brand SMT, which has previously called their tomatoes San Marzano, despite not actually being that. They engage(d) in various shady practices so I personally avoid them and suggest others do too.
Odd. Either I have terrible tastebuds or it doesn't matter in this particular application, but last time I made sauce with San Marzano vs generic tomatoes no one could tell the difference.
Someone more experienced want to pipe in and help my ignorance?
Depending on how you cooked it, the difference might be subtle enough that only someone familiar with it would notice.
Try eating the tomato raw, like an apple. A good tomato is wonderful with just a sprinkle of salt.
I only started noticing the difference after I grew my own heirloom tomatoes. I was amazed when I ate my first harvest, fresh off the plant. I had never tasted a tomato before in my life! Basic supermarket tomatoes just taste like water.
Not experienced, but (1) unless tomatoes feature prominently in a recipe, the details of their flavour won't have that much impact, (2) for any expensive protected-origin kind of stuff, there's a chance somebody just took the plain stuff and relabelled it.
For more info, see http://cooking.stackexchange.com/questions/68538/are-these-t...