The owner of Hello Sexy in Fyshwick, Steve Mason, said the festival was no longer the ''big giant killer of January that it once was''.

''It's not even really worth getting excited about for us any more,'' he said.

Mr Mason said eight years ago the store would rake in 300 per cent more money over the festival period, but this year's windfall would be closer to 20 per cent.

The drop-off coincides with a 20 per cent fall in crowd numbers for this year's Summernats, which promoter Chic Henry said could spell the end of the festival.

Mr Mason's sombre analysis was reflected by other traders.

Adult World sales assistant Hannah Dickie said there was only a slight increase in sales.

''It's nowhere near what it used to be a few years ago,'' Ms Dickie said.

Nevertheless, during the four-day festival Adult World was still expecting to double the number of customers coming through the doors.

Owner of Mustang Ranch Peter Chan said they had seen a 10 per cent increase in customers, and was not anticipating much of a boom as punters left Canberra today.

Staff at Adam 'N Eve, who pitch to the Summernats crowd more than perhaps any other trader, also suggested the festival crowds were not coming through their doors.

Mr Mason said tighter Summernats security significantly contributed to the decline of the festival trade.

''The guys that used to patronise the shops don't really come to the Summernats any more, [the organisers have] managed to make it more of a family-oriented event,'' he said.

Mr Mason also said he believed nationwide growth in the sex trade made people less likely to treat Canberra as a porn mecca.

''When we started 13 years ago, we had a database of wholesale clients that we used to sell to of about 50 or 60 shops across Australia, and now there's something like 1000,'' he said.

''It's definitely a growth industry.''

He also said the global financial crisis was taking its toll.

This was despite suggestions from the head of the industry lobby group the Eros Foundation, Fiona Patten, that the sex industry was recession-proof.

But for a group of Geelong men in town for the Summernats, heading down to Fyshwick to pick up some DVDs was a must. Brothers Mick and Brad Collett, 36 and 38 respectively, and Scott Barry, 30, will head back home today with some souvenirs the wives and girlfriends may not appreciate.

''I've got a bit of Barely Legal, and some Miss Strap-on,'' Mick said, pulling the DVDs from a black bag.

The group has made the annual trip to the Summernats for most of two decades, and Mick said the Fyshwick detour was a ritual.

And if the event moved to Sydney?

''We'd go to Sydney but we'll have to stop here on the way,'' Brad said.