The produce check on BME is crap! If you read through the job it even states you're more likely to be paid £4/£5 because it's based on the supermarkets stock and not your effort. And if they say £4/£5 it's probably less than that in some cases. The upto £11.50 is just there to lure folks in.
The Coco-Cola jobs on Roamler are crap! That's why they keep increasing the fee. They want photography style photos in small independents that don't know or care about Roamler. It makes it extremely difficult to complete undercover which is really the way you want to go about these jobs. The letter attached is not authoritative enough and counts for jack. If it was my shop, I would want to see ID or at least a telephone number before random folks start taking photos!
I'm actually having a task mission melt down at the minute. Nothing on T360 for weeks. The quietest it's ever been I'd say and I've been doing it for 2 years. Streetspotr has Lidl jobs but I was completing them for £20 last month, this month they are £6.. might increase. Field agent is slow but one to watch as the recent fragrance job was spot on.
I recommend registering with Assosia and Frontier. The jobs are similar to the task apps but they email the work out. If you're quick to respond, you can book as many jobs as you can complete on a set date. No timer. I've manage about £160 with them so far this month.