There is a panel in the game to see popular products directly? without entering each city ?
How to see the popular goods:
1) if someone (perhaps your alt) promulgates the trend at a trader npc it shows the trend for that city, in the "popular channel" tab (3rd tab in from the right) of the chat screen and will stay in that screen (unless the screen is cleared by the player) until that particular trend is over/expired.
Also, when you promulgate it tells you how much (game) time is left until the trend ends.
In the old days you use to see many alts camped at a lot of the trader npcs just for this purpose;
so they didn't have to run inside each city.
2) buy business spy cards from the in game item mall (Dollar sign in ships wheel >> Item type tab).
You can use them anywhere** - however the trend will appear in the middle of your screen 1 time, and in your "Public" general chat channel (far left tab) - no one else will see it.
[but it is annoying when people start talking around you or in guild as ALL chat goes to that channel]
**I do not suggest using them while moving/ sailing.
If you change scenes or if your ship (when auto tracking) turns, the info/ selection screens will be closed.
You will use 1 card to look at one city
So you do go through a lot of cards, but they are relatively cheep and one good trade run will pay for them.
(I think there are 48 or 50 Trade cities ie. cities that have a trader npc)
I will also note that sometimes a good is not popular during a trend period.
this happens most often with the Amethyst, Emerald, Picea, Gold, goods that are the money makers and that give you 500 world ocean points.
[Guides] Trend Trading Guides & TPC Exchange
[Guides] 2014 - Trader Goods and Ports Guide