The biggest lesson seems to be eat slowly and give yourself plenty of time to eat and digest your meals and stay away from excess fats and sugars.
Everyone's experience and tolerance level (in relation to dumping) is different but,
for me, I can report that things that are "too high" in sugar are:
-- apple juice
-- orange juice
(probably any pure/concentrated fruit juice)
-- ice cream
-- Slimfast and other protein shakes
(can just about tolerate but do give me 'mild' dumping like hot sweats and dizziness)
-- flapjacks **
** Or one particular flapjack I tried some months ago was a very sugary specimen with a very high GI level (sugar that hits the system straight away).
Have also heard about a sleever dumping on:
-- fresh pineapple (pieces)
(So again be wary of high sugar fruit and fruit juices.... but I am fine with low GI bananas.)
I have found many other foods (that do contain sugar but lower GI) to be fine including:
-- Belvita and Digestive biscuits
-- small occasional amounts of chocolate
(not sure if there is something about the way that milk choc is made that makes it slightly lower GI than, say, ice cream)
-- wafer type bars
-- sweetened porridge
Some of us avoid mentioning too much online exactly *what* has (or has not) caused us these problems for fear that
Aunty Karlos will come along and give us an ear bashing for having *dared* to try out all those naughty things in the first place

..... but I don't think any of us are eating tonnes of rubbish carbs every day -- but in the course of "normal life" it is pretty normal 3 - 6 months post op to start
'trying' things again (things that you used to like, or palatable treats that are being eaten in company in a social setting etc) -- and it is in these occasional 'try-out' times that we find what works and what doesn't.